In particular, this get rid of the ugly -? option that argp adds by
default, and we also remove -V so that we can use it for something
else later.

* src/bin/common_setup.cc, src/bin/common_setup.hh (misc_argp):
Provide support for --help/--version/--usage output, replacing argp's
default builting version.
* src/bin/genltl.cc, src/bin/ltl2tgba.cc, src/bin/ltl2tgta.cc,
src/bin/ltlcheck.cc, src/bin/ltlfilt.cc, src/bin/randltl.cc:
Call argp_parse() with ARGP_NO_HELP, and use misc_argp instead.