* 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.
* bin/autfilt.cc: Translate each word as an automaton once,
and do not make a global product of all of them.
* spot/twaalgos/word.cc: Register the atomic propositions used by the
word when converting it into an automaton.
* tests/core/acc_word.test: Add a test case that used to fail, and
another test that make sure some words are not accepted.
Suggested by Matthias Heizmann. Fixes#109.
* NEWS: notify the new option
* THANKS: add Matthias Heizmann
* bin/autfilt.cc: add new option --accept-word=WORD which filters
automata that accept WORD
* doc/org/autfilt.org: add an example of the new option
* tests/Makefile.am: add core/acc_word.test to the list of test files
* tests/core/acc_word.test: test some uses of the new option
