* spot/misc/optionmap.hh, spot/misc/optionmap.cc (report_unused_options,
set_, set_set_): New methods.
* bin/autfilt.cc, bin/dstar2tgba.cc, bin/ltl2tgba.cc,
bin/ltl2tgta.cc: Call report_unused_options().
* tests/core/ltlcross2.test, tests/core/readsave.test: Fix typos in
options.
* tests/core/minusx.test: New file.
* tests/Makefile.am: Add it.
* NEWS: Mention this.