* wrap/python/spot.py: Implement it.  Also report non-zero
exit using CalledProcessError.
* wrap/python/tests/automata-io.ipynb, wrap/python/tests/piperead.ipynb:
Adjust.
* NEWS: Mention the change.

* src/tests/unambig.test: New test case.  Reported by Ming-Hsien Tsai.
* src/twaalgos/sccfilter.cc: Always create an initial state.
* src/twaalgos/isunamb.cc: Speed up on empty languages.
* NEWS, THANKS: Update.

This simplifies the use of the spot.postprocessor object.

* wrap/python/spot.py: Add it.
* wrap/python/tests/automata.ipynb: Use it.
* NEWS: Mention it.

This is a bug:

    % ltlfilt -f 'a W b' --unabbreviate=WR
    a U (b | (a W b))

* src/tl/unabbrev.cc: Here.
* src/tests/unabbrevwm.test: Harden test case.
* wrap/python/tests/randltl.ipynb: Adjust expected output.
* NEWS: Mention the fix.

* wrap/python/spot_impl.i (get_name, set_name): New methods for twa.
* wrap/python/tests/remfin.py: Test them.
* wrap/python/ajax/spotcgi.in: Use set_name().
* NEWS: Mention it.

* doc/org/tut01.org, doc/tl/tl.tex, src/bin/common_r.hh,
src/bin/ltlfilt.cc, src/tests/equalsf.cc, src/tests/ikwiad.cc,
src/tests/randtgba.cc, src/tests/reduc.cc, src/tests/syntimpl.cc,
src/tl/nenoform.cc, src/tl/randomltl.cc, src/tl/randomltl.hh,
src/tl/simplify.cc, src/tl/simplify.hh, src/twaalgos/ltl2tgba_fm.cc,
src/twaalgos/ltl2tgba_fm.hh, src/twaalgos/stutter.cc,
src/twaalgos/translate.cc, src/twaalgos/translate.hh,
wrap/python/ajax/spotcgi.in, wrap/python/spot.py,
wrap/python/tests/interdep.py: Rename ltl_simplifier to tl_simplifier.
* NEWS: Mention it.

* debian/rules: Build for all supported python3 versions.
* NEWS: Mention it.

* src/parseaut/parseaut.yy: Add and the a check_version() function.
* src/tests/parseaut.test: Test it.
* NEWS: Mention it.

This additionally fixes #107.

* src/bin/ltlgrind.cc: Fix handling for FILEANAME/COL.  Document FORMAT
in --help.  Assume -F for arguments given without options.
* src/tests/ltlgrind.test: Add two tests.
* NEWS: Mention this.

This is motivated by an email from Fanda.

* src/bin/common_post.cc, src/bin/common_post.hh: Add variables to
detect when level or pref are sets.
* src/bin/autfilt.cc: Adjust default for pref/sets.
* src/tests/readsave.test: Add test cases.
* NEWS: Mention it.

* src/bin/autfilt.cc: Add option --complete.
* src/twaalgos/complete.cc: Better handling of 0-edge automata.
* src/tests/complement.test: New file.
* src/tests/Makefile.am: Add it.

* src/twaalgos/randomgraph.cc: Replace an assertion by an exception.
* src/bin/randaut.cc: Diagnose -Q0.
* src/tests/randaut.test: Test it.
* NEWS: Mention the bug.

* src/twaalgos/sccfilter.hh,
src/twaalgos/sccfilter.cc (scc_filter_states): Remove useless acceptance
marks while preserving state-based acceptance.  Add a new argument
to specify if all useless mark have to be removed, like for scc_filter.
* src/twaalgos/simulation.cc: Use the new parameter.
* src/twaalgos/postproc.cc: Likewise.  Also call do_scc_filter even
after WDBA simplification to cleanup trivial SCCs.  Preserve state-based
acceptance for weak automata.
* src/tests/readsave.test: Add one test.
* src/tests/dstar.test, src/tests/prodor.test, src/tests/remfin.test,
src/tests/sim3.test, wrap/python/tests/automata.ipynb,
wrap/python/tests/piperead.ipynb: Adjust expected output.
* NEWS: Mention the change.

The previous code was sometime doing the work of remove_fin() in
addition to complementing the acceptance conditions.  This separate
the two operations clearly.  Also the specialized code for
complementing weak automata is now a specialized code for remove_fin()
on weak automata.

* src/twaalgos/dtgbacomp.hh, src/twaalgos/dtgbacomp.cc: Rename as ...
* src/twaalgos/complement.hh, src/twaalgos/complement.cc: ... these.
* src/twaalgos/Makefile.am: Adjust.
* src/twaalgos/complement.hh (dtgba_complement): Rename as ...
(dtwa_complement): ... this, and restrict the purpose to completion
and accetance complementation.  Further acceptance simplification
can be done with remove_fin() and to_generalized_buchi().
* src/twaalgos/remfin.cc (remove_fin): Specialize handling of weak
automata using the code that was originally in dtgba_complement().
Also mark the output as state-based when the input has to Inf.
* src/twaalgos/postproc.cc, src/twaalgos/postproc.hh: Make sure
scc_filter is always called after to_generalized_buchi().
* bench/stutter/stutter_invariance_randomgraph.cc,
src/bin/ltlcross.cc, src/tests/ikwiad.cc, src/twaalgos/minimize.cc,
src/twaalgos/powerset.cc, src/twaalgos/stutter.cc: Adjust usage.
* src/tests/dstar.test, src/tests/ltl2dstar4.test,
src/tests/remfin.test: Adjust expected outputs.
* wrap/python/spot_impl.i: Export dtwa_complement().

Fixes #105.

* src/bin/common_trans.cc (quote_shell_string): Move ...
* src/misc/escape.cc, src/misc/escape.hh (quote_shell_string):
... here.
* wrap/python/spot_impl.i: Wrap escape.hh.
* wrap/python/spot.py: Implement formula.__format__.
* wrap/python/tests/ltlsimple.py: Test it.
* NEWS, doc/org/tut01.org, wrap/python/tests/formulas.ipynb: Document
it.

* NEWS, configure.ac, doc/org/setup.org: Bump version.
* doc/org/index.org: Better wording of a link.

* src/ltlparse/public.hh: Rename as...
* src/tl/parse.hh: ... this.
* src/ltlparse/: Rename as...
* src/parsetl/: ... this.
* NEWS: Mention the change.
* README, configure.ac, doc/org/tut01.org, doc/org/tut02.org,
doc/org/tut03.org, doc/org/tut10.org, src/Makefile.am,
src/bin/common_finput.cc, src/bin/common_finput.hh, src/bin/ltl2tgta.cc,
src/kripkeparse/kripkeparse.yy, src/parseaut/parseaut.yy,
src/tests/checkpsl.cc, src/tests/checkta.cc,
src/tests/complementation.cc, src/tests/consterm.cc,
src/tests/emptchk.cc, src/tests/equalsf.cc, src/tests/ikwiad.cc,
src/tests/kind.cc, src/tests/length.cc, src/tests/ltlprod.cc,
src/tests/ltlrel.cc, src/tests/randtgba.cc, src/tests/readltl.cc,
src/tests/reduc.cc, src/tests/syntimpl.cc, src/tests/tostring.cc,
src/tl/Makefile.am, src/twaalgos/lbtt.cc, wrap/python/spot_impl.i,
iface/ltsmin/modelcheck.cc: Adjust.

* src/twaalgos/dupexp.cc, src/twaalgos/dupexp.hh: Rename to...
* src/twaalgos/copy.cc, src/twaalgos/copy.hh: ... these.
Get rid of dupexp_bfs, rename dupexp_dfs as copy, and add
an option to preserve named states.
* src/twaalgos/Makefile.am, src/tests/dupexp.test,
src/tests/ikwiad.cc, src/tests/sccsimpl.test,
src/twa/twagraph.hh, src/twaalgos/dot.cc,
src/twaalgos/stutter.cc, wrap/python/spot_impl.i: Adjust.
* NEWS: Mention this change.

* NEWS: Mention it.
* bench/stutter/stutter_invariance_formulas.cc,
bench/stutter/stutter_invariance_randomgraph.cc, doc/mainpage.dox,
doc/org/tut01.org, doc/org/tut02.org, doc/org/tut10.org, doc/tl/tl.tex,
iface/ltsmin/ltsmin.cc, iface/ltsmin/ltsmin.hh,
iface/ltsmin/modelcheck.cc, src/bin/autfilt.cc,
src/bin/common_aoutput.cc, src/bin/common_aoutput.hh,
src/bin/common_finput.cc, src/bin/common_finput.hh,
src/bin/common_output.cc, src/bin/common_output.hh, src/bin/common_r.hh,
src/bin/common_trans.cc, src/bin/common_trans.hh, src/bin/dstar2tgba.cc,
src/bin/genltl.cc, src/bin/ltl2tgba.cc, src/bin/ltl2tgta.cc,
src/bin/ltlcross.cc, src/bin/ltldo.cc, src/bin/ltlfilt.cc,
src/bin/ltlgrind.cc, src/bin/randaut.cc, src/bin/randltl.cc,
src/kripke/kripkeexplicit.cc, src/kripke/kripkeexplicit.hh,
src/kripkeparse/kripkeparse.yy, src/kripkeparse/public.hh,
src/ltlparse/fmterror.cc, src/ltlparse/ltlparse.yy,
src/ltlparse/ltlscan.ll, src/ltlparse/parsedecl.hh,
src/ltlparse/public.hh, src/parseaut/parseaut.yy,
src/parseaut/public.hh, src/tests/checkpsl.cc, src/tests/checkta.cc,
src/tests/complementation.cc, src/tests/consterm.cc,
src/tests/emptchk.cc, src/tests/equalsf.cc, src/tests/ikwiad.cc,
src/tests/kind.cc, src/tests/length.cc, src/tests/ltlprod.cc,
src/tests/ltlrel.cc, src/tests/parse.test,
src/tests/parse_print_test.cc, src/tests/randtgba.cc,
src/tests/readltl.cc, src/tests/reduc.cc, src/tests/syntimpl.cc,
src/tests/taatgba.cc, src/tests/tostring.cc, src/tests/tostring.test,
src/tl/apcollect.cc, src/tl/apcollect.hh, src/tl/contain.cc,
src/tl/contain.hh, src/tl/declenv.cc, src/tl/declenv.hh,
src/tl/defaultenv.cc, src/tl/defaultenv.hh, src/tl/dot.cc,
src/tl/dot.hh, src/tl/environment.hh, src/tl/exclusive.cc,
src/tl/exclusive.hh, src/tl/formula.cc, src/tl/formula.hh,
src/tl/length.cc, src/tl/length.hh, src/tl/mark.cc, src/tl/mark.hh,
src/tl/mutation.cc, src/tl/mutation.hh, src/tl/nenoform.cc,
src/tl/nenoform.hh, src/tl/print.cc, src/tl/print.hh,
src/tl/randomltl.cc, src/tl/randomltl.hh, src/tl/relabel.cc,
src/tl/relabel.hh, src/tl/remove_x.cc, src/tl/remove_x.hh,
src/tl/simpfg.cc, src/tl/simpfg.hh, src/tl/simplify.cc,
src/tl/simplify.hh, src/tl/snf.cc, src/tl/snf.hh, src/tl/unabbrev.cc,
src/tl/unabbrev.hh, src/twa/bdddict.cc, src/twa/bdddict.hh,
src/twa/bddprint.cc, src/twa/formula2bdd.cc, src/twa/formula2bdd.hh,
src/twa/taatgba.cc, src/twa/taatgba.hh, src/twa/twa.hh,
src/twa/twagraph.cc, src/twa/twagraph.hh, src/twaalgos/compsusp.cc,
src/twaalgos/compsusp.hh, src/twaalgos/ltl2taa.cc,
src/twaalgos/ltl2taa.hh, src/twaalgos/ltl2tgba_fm.cc,
src/twaalgos/ltl2tgba_fm.hh, src/twaalgos/minimize.cc,
src/twaalgos/minimize.hh, src/twaalgos/neverclaim.cc,
src/twaalgos/postproc.cc, src/twaalgos/postproc.hh,
src/twaalgos/powerset.cc, src/twaalgos/powerset.hh,
src/twaalgos/randomgraph.cc, src/twaalgos/randomgraph.hh,
src/twaalgos/relabel.cc, src/twaalgos/relabel.hh,
src/twaalgos/remprop.cc, src/twaalgos/remprop.hh, src/twaalgos/stats.cc,
src/twaalgos/stats.hh, src/twaalgos/stutter.cc, src/twaalgos/stutter.hh,
src/twaalgos/translate.cc, src/twaalgos/translate.hh,
wrap/python/spot_impl.i: Remove the ltl namespace.

The ltl prefix does not make a lot of sens anymore (since we
support psl as well).  ltlast/ and ltlenv/ were almost empty.
And ltlvisit/ did not contain any visitor anymore.

* src/ltlvisit/, src/ltlast/, src/ltlenv/: Merge into...
* src/tl/: ...this.
* NEWS: Mention the change.
* README, bench/stutter/stutter_invariance_formulas.cc,
bench/stutter/stutter_invariance_randomgraph.cc, configure.ac,
doc/org/tut01.org, doc/org/tut02.org, doc/org/tut10.org, doc/tl/tl.tex,
iface/ltsmin/ltsmin.hh, iface/ltsmin/modelcheck.cc, src/Makefile.am,
src/bin/autfilt.cc, src/bin/common_output.cc, src/bin/common_output.hh,
src/bin/common_r.hh, src/bin/common_trans.cc, src/bin/genltl.cc,
src/bin/ltl2tgba.cc, src/bin/ltl2tgta.cc, src/bin/ltlcross.cc,
src/bin/ltldo.cc, src/bin/ltlfilt.cc, src/bin/ltlgrind.cc,
src/bin/randltl.cc, src/kripke/kripkeexplicit.hh,
src/kripkeparse/public.hh, src/parseaut/public.hh, src/priv/accmap.hh,
src/ta/taexplicit.hh, src/ta/tgtaexplicit.hh, src/tests/equalsf.cc,
src/tests/ikwiad.cc, src/tests/length.cc, src/tests/ltlrel.cc,
src/tests/randtgba.cc, src/tests/readltl.cc, src/tests/reduc.cc,
src/tests/syntimpl.cc, src/tests/taatgba.cc, src/tests/tostring.cc,
src/tests/twagraph.cc, src/twa/acc.hh, src/twa/bdddict.cc,
src/twa/bdddict.hh, src/twa/bddprint.cc, src/twa/taatgba.cc,
src/twa/taatgba.hh, src/twa/twa.hh, src/twa/twagraph.cc,
src/twa/twagraph.hh, src/twa/twasafracomplement.cc,
src/twaalgos/compsusp.cc, src/twaalgos/compsusp.hh,
src/twaalgos/dtgbasat.cc, src/twaalgos/hoa.cc,
src/twaalgos/isweakscc.cc, src/twaalgos/lbtt.cc,
src/twaalgos/ltl2taa.cc, src/twaalgos/ltl2taa.hh,
src/twaalgos/ltl2tgba_fm.cc, src/twaalgos/ltl2tgba_fm.hh,
src/twaalgos/minimize.hh, src/twaalgos/neverclaim.cc,
src/twaalgos/randomgraph.hh, src/twaalgos/relabel.hh,
src/twaalgos/remprop.hh, src/twaalgos/stats.cc, src/twaalgos/stutter.cc,
src/twaalgos/translate.hh, wrap/python/spot_impl.i,
src/ltlparse/ltlparse.yy, src/ltlparse/public.hh: Adjust.

* src/twaalgos/product.cc, src/twaalgos/product.hh: Implement
the variance.
* src/bin/autfilt.cc: Expose it.
* src/tests/prodor.test: New file.
* src/tests/Makefile.am: Add it.
* NEWS: Mention it.

Flatten the formula ltl::formula hiearchy into a single ltl::vnode that
has an enumerator to distinguish the types of node, and a common
interface to access children, update reference counts, etc.  The
ltl::formula class is now a thin wrapper around an ltl::vnode pointer to
keep track of reference counts automatically.  Visitor are not used
anymore; we now have map() and traversor() methods that are more
concise.

This basically fixes #43, but should be followed by some fine tuning
that should now be localized to the formula.hh and formula.cc files.

Some statistics about this patch.  I started working on it on Sep 9, had
a first compiling version two weeks later on Sep 22, and it then took 5
days to fixes the ~70 distincts bugs that were introduced during the
conversion.  About 13200 lines were modified, and one third of those
were removed.

* src/ltlast/formula.cc, src/ltlast/formula.hh: Complete rewrite,
including what was in separate nearby files.
* src/ltlast/allnodes.hh, src/ltlast/atomic_prop.cc,
src/ltlast/atomic_prop.hh, src/ltlast/binop.cc, src/ltlast/binop.hh,
src/ltlast/bunop.cc, src/ltlast/bunop.hh, src/ltlast/constant.cc,
src/ltlast/constant.hh, src/ltlast/multop.cc, src/ltlast/multop.hh,
src/ltlast/unop.cc, src/ltlast/unop.hh, src/ltlvisit/dump.cc,
src/ltlvisit/dump.hh, src/ltlast/predecl.hh: Delete these files.  Their
feature have been merged in formula.hh and formula.cc.
* src/ltlast/visitor.hh, src/ltlvisit/clone.cc, src/ltlvisit/clone.hh,
src/ltlvisit/dump.hh, src/ltlvisit/postfix.cc, src/ltlvisit/postfix.hh:
Delete these files, as we do not use visitors anymore.
* bench/stutter/stutter_invariance_formulas.cc,
bench/stutter/stutter_invariance_randomgraph.cc, doc/org/tut01.org,
doc/org/tut02.org, doc/org/tut10.org, doc/org/tut22.org,
iface/ltsmin/ltsmin.cc, iface/ltsmin/ltsmin.hh,
iface/ltsmin/modelcheck.cc, src/bin/autfilt.cc,
src/bin/common_aoutput.cc, src/bin/common_aoutput.hh,
src/bin/common_finput.cc, src/bin/common_finput.hh,
src/bin/common_output.cc, src/bin/common_output.hh,
src/bin/common_trans.cc, src/bin/common_trans.hh, src/bin/dstar2tgba.cc,
src/bin/genltl.cc, src/bin/ltl2tgba.cc, src/bin/ltl2tgta.cc,
src/bin/ltlcross.cc, src/bin/ltldo.cc, src/bin/ltlfilt.cc,
src/bin/ltlgrind.cc, src/bin/randaut.cc, src/bin/randltl.cc,
src/kripke/kripkeexplicit.cc, src/kripke/kripkeexplicit.hh,
src/kripkeparse/kripkeparse.yy, src/ltlast/Makefile.am,
src/ltlenv/declenv.cc, src/ltlenv/declenv.hh, src/ltlenv/defaultenv.cc,
src/ltlenv/defaultenv.hh, src/ltlenv/environment.hh,
src/ltlparse/ltlparse.yy, src/ltlparse/public.hh,
src/ltlvisit/Makefile.am, src/ltlvisit/apcollect.cc,
src/ltlvisit/apcollect.hh, src/ltlvisit/contain.cc,
src/ltlvisit/contain.hh, src/ltlvisit/dot.cc, src/ltlvisit/dot.hh,
src/ltlvisit/exclusive.cc, src/ltlvisit/exclusive.hh,
src/ltlvisit/length.cc, src/ltlvisit/length.hh, src/ltlvisit/mark.cc,
src/ltlvisit/mark.hh, src/ltlvisit/mutation.cc,
src/ltlvisit/mutation.hh, src/ltlvisit/nenoform.cc,
src/ltlvisit/nenoform.hh, src/ltlvisit/print.cc, src/ltlvisit/print.hh,
src/ltlvisit/randomltl.cc, src/ltlvisit/randomltl.hh,
src/ltlvisit/relabel.cc, src/ltlvisit/relabel.hh,
src/ltlvisit/remove_x.cc, src/ltlvisit/remove_x.hh,
src/ltlvisit/simpfg.cc, src/ltlvisit/simpfg.hh,
src/ltlvisit/simplify.cc, src/ltlvisit/simplify.hh, src/ltlvisit/snf.cc,
src/ltlvisit/snf.hh, src/ltlvisit/unabbrev.cc, src/ltlvisit/unabbrev.hh,
src/parseaut/parseaut.yy, src/ta/taexplicit.cc, src/ta/tgtaexplicit.cc,
src/taalgos/minimize.cc, src/taalgos/tgba2ta.cc, src/tests/bare.test,
src/tests/checkpsl.cc, src/tests/checkta.cc,
src/tests/complementation.cc, src/tests/consterm.cc,
src/tests/emptchk.cc, src/tests/equalsf.cc, src/tests/ikwiad.cc,
src/tests/isop.test, src/tests/kind.cc, src/tests/length.cc,
src/tests/ltldo.test, src/tests/ltlfilt.test, src/tests/ltlgrind.test,
src/tests/ltlprod.cc, src/tests/ltlrel.cc,
src/tests/parse_print_test.cc, src/tests/parseaut.test,
src/tests/parseerr.test, src/tests/randtgba.cc, src/tests/readltl.cc,
src/tests/reduc.cc, src/tests/syntimpl.cc, src/tests/taatgba.cc,
src/tests/tostring.cc, src/tests/twagraph.cc, src/tests/utf8.test,
src/twa/acc.cc, src/twa/bdddict.cc, src/twa/bdddict.hh,
src/twa/bddprint.cc, src/twa/formula2bdd.cc, src/twa/formula2bdd.hh,
src/twa/taatgba.cc, src/twa/taatgba.hh, src/twa/twa.cc, src/twa/twa.hh
src/twa/twagraph.cc, src/twa/twagraph.hh, src/twa/twasafracomplement.cc,
src/twaalgos/compsusp.cc, src/twaalgos/compsusp.hh,
src/twaalgos/dtgbasat.cc, src/twaalgos/hoa.cc, src/twaalgos/lbtt.cc,
src/twaalgos/ltl2taa.cc, src/twaalgos/ltl2taa.hh,
src/twaalgos/ltl2tgba_fm.cc, src/twaalgos/ltl2tgba_fm.hh,
src/twaalgos/minimize.cc, src/twaalgos/minimize.hh,
src/twaalgos/neverclaim.cc, src/twaalgos/postproc.cc,
src/twaalgos/postproc.hh, src/twaalgos/powerset.cc,
src/twaalgos/powerset.hh, src/twaalgos/randomgraph.cc,
src/twaalgos/remprop.cc, src/twaalgos/remprop.hh, src/twaalgos/stats.cc,
src/twaalgos/stats.hh, src/twaalgos/stutter.cc, src/twaalgos/stutter.hh,
src/twaalgos/translate.cc, src/twaalgos/translate.hh,
wrap/python/ajax/spotcgi.in, wrap/python/spot.py,
wrap/python/spot_impl.i, wrap/python/Makefile.am,
wrap/python/tests/automata-io.ipynb, wrap/python/tests/formulas.ipynb,
wrap/python/tests/ltl2tgba.py, wrap/python/tests/ltlparse.py,
wrap/python/tests/ltlsimple.py, wrap/python/tests/randltl.ipynb: Adjust
to use the new interface.
* src/sanity/style.test: Accept more C++11 patterns.
* NEWS: Mention the change.

* NEWS: Mention the changes.
* doc/org/autfilt.org, doc/org/dstar2tgba.org,
doc/org/ltlcross.org, doc/org/tools.org, doc/org/tut20.org,
src/bin/man/dstar2tgba.x, src/bin/man/ltlcross.x: Adjust
documentation.
* src/bin/common_trans.cc: Use %O instead of %D, but keep %D
hidden for backward compatibility.

This was suggested by one of the reviewers of our LPAR'15 paper.

* src/twaalgos/dtgbasat.cc, src/twaalgos/dtgbasat.hh: Implement
the colored option.
* src/tests/satmin2.test: Test it.
* doc/org/satmin.org, NEWS: Document it.

* NEWS, configure.ac, doc/org/setup.org: Update version.

* src/tests/bitvect.cc: Fix it, it was failing an assert() on 32bit
architectures because the subset test was done in the wrong order.
Reported by Christopher Ziegler.
* NEWS: Mention it.

Fixes #96, reported by Vitus Lam & Christopher Ziegler.

* src/bin/ltlcross.cc: Catch std::bad_alloc, skip those
products and the related tests.  Display a count of
those skipped tests at the end.
* NEWS: Mention it.
* src/tests/ltlcross3.test: Adjust expected error
message.

Reported by Christopher Ziegler.

* src/tests/uniq.test: For LC_ALL=C before sort.

This implies learning alternative rules for G, and W as well, since
those would use R.

Fixes #103.  Suggested by Joachim Klein.

* src/ltlvisit/unabbrev.cc, src/ltlvisit/unabbrev.hh: Implement the
new rules.
* doc/tl/tl.tex: Document the rules.
* src/tests/unabbrevwm.test: Test them.
* src/bin/ltlfilt.cc, NEWS: Mention that --unabbreviate accepts R.

* src/ltlparse/ltlscan.ll: Adjust parser.
* src/ltlvisit/print.cc: Adjust printer.
* src/tests/ltlfilt.test: Add some tests.
* NEWS: Mention it.

(Upcoming GCC 6.)

* src/misc/intvcmp2.cc: Here.
* NEWS: Mention it.

* src/bin/ltlfilt.cc: Add option --unabbreviate.
* src/tests/ltlfilt.test: Add a test case.
* NEWS: Mention it.

* src/ltlvisit/lunabbrev.cc, src/ltlvisit/lunabbrev.hh,
src/ltlvisit/tunabbrev.cc, src/ltlvisit/tunabbrev.hh,
src/ltlvisit/wmunabbrev.cc, src/ltlvisit/wmunabbrev.hh: Delete.
* src/ltlvisit/unabbrev.cc, src/ltlvisit/unabbrev.hh: New files.
* src/ltlvisit/Makefile.am: Adjust.
* src/ltlvisit/print.cc, src/tests/equalsf.cc, src/tests/Makefile.am,
src/twaalgos/ltl2taa.cc, wrap/python/spot_impl.i, src/bin/ltlfilt.cc:
Adjust callers.
* src/ltlvisit/contain.cc, src/tests/syntimpl.cc: Remove useless
include.
* wrap/python/tests/formulas.ipynb: New test cases.
* doc/tl/tl.tex: Group all rules in a single section.
* NEWS: Mention it.