ltlfilt: implement --reject-word and --accept-word
* bin/common_range.hh: Store the common definition of words. * bin/autfilt.cc: Use it. * bin/ltlfilt.cc: Likewise, and implement those two options. * tests/core/acc_word.test: Test them. * doc/org/autfilt.org: Augment the last example to point out that it can now be done with ltlfilt. * NEWS: Mention the new options.