* src/bin/man/autfilt.x, src/bin/man/dstar2tgba.x,
src/bin/man/ltl2tgba.x, src/bin/man/ltlcross.x,
src/bin/man/ltlgrind.x, src/bin/man/randltl.x, src/bin/man/spot-x.x:
Improve typesetting and cross-references.
* tools/help2man: Adjust to better detect the optional arguments.
Detect options that are not separated from their description by two
spaces. Argp output some of those.
* tools/man2html.pl: New file.
* Makefile.am: Distribute it.
* src/bin/ltlfilt.cc: Fix description of --define.
* src/bin/ltlgrind.cc: Fix duplicate description for --help and
--version. Reorder --help output slightly.
* NEWS: Mention the few fixes.
