collaboration diagrams.
* doc/mainpage.dox: Typo.

* src/tgba/state.hh (state::as_bdd): Delete.
* src/tgba/tgbaproduct.hh (state_bdd_product): Inherit from state,
not state_bdd.
(state_bdd_product::state_bdd_product): Adjust.
* src/tgba/tgbaproduct.cc (state_bdd_product::state_bdd_product):
Adjust.

* src/tgba/succiter.hh (tgba_bdd_succ_iterator::done):
Mark as const.
* src/tgba/succiterconcrete.cc
(tgba_succ_iterator_concrete::done): Likewise.
* src/tgba/succiterconcrete.hh
(tgba_succ_iterator_concrete::done): Likewise.
* src/tgba/tgbaexplicit.cc
(tgba_explicit_succ_iterator::done): Likewise.
* src/tgba/tgbaexplicit.hh
(tgba_explicit_succ_iterator::done): Likewise.
* src/tgba/tgbaproduct.cc
(tgba_product_succ_iterator::done): Likewise.
* src/tgba/tgbaproduct.hh
(tgba_product_succ_iterator::done): Likewise.
* src/tgba/tgbatranslateproxy.hh
(tgba_translate_proxy_succ_iterator::done): Likewise.
* src/tgba/tgbatranslateproxy.cc
(tgba_translate_proxy_succ_iterator::done): Likewise.

* src/tgba/succiterconcrete.cc
(tgba_succ_iterator_concrete::next): Call bdd_satoneset
on data_.varandnext_set.  The previous implementation
was wrong for GFa.
* src/tgba/tgbabddcoredata.hh: Declare varandnext_set.
* src/tgba/tgbabddcoredata.cc: Handle varandnext_set.

* doc/Makefile.am (spotref.pdf): New rule.
(EXTRA_DIST): Add spotref.pdf.

* doc/Makefile.am (EXTRA_DIST): Add mainpage.dox.
* doc/Doxyfile.in (INPUT): Add @srcdir@/mainpage.dox

or configure.ac changes.  Distribute the html doc.
* doc/Doxyfile.in (EXCLUDE_PATTERNS): Complete with
useless Bison classes.
(FILE_PATTERNS): Remove *.cc files.

src/ltlast/constant.hh, src/ltlast/formula.hh,
src/ltlast/multop.hh, src/ltlast/unop.hh, src/ltlast/visitor.hh,
src/ltlenv/defaultenv.hh, src/ltlenv/environment.hh,
src/ltlparse/public.hh, src/ltlvisit/clone.hh,
src/ltlvisit/dotty.hh, src/ltlvisit/dump.hh,
src/ltlvisit/equals.hh, src/ltlvisit/lunabbrev.hh,
src/ltlvisit/nenoform.hh, src/ltlvisit/tunabbrev.hh: Add
Doxygen comments.
* src/visitor.hh: Do not use const_sel.  This clarify
the code and helps Doxygen.

* doc/Makefile.am, doc/Doxyfile.in: New files.
* Makefile.am (SUBDIRS): Add doc.