* spot/twaalgos/contains.hh, spot/twaalgos/contains.cc
(containment_select_version): New function.
(contains): Use it.
* spot/twa/twa.cc (exclusive_word): Likewise.
* bin/autfilt.cc (--included-in): Adjust to use forq depending
on containement_select_version.
* bin/man/spot-x.x: Adjust documentation of
CONTAINMENT_SELECT_VERSION.
* tests/core/included.test, tests/python/forq_contains.py: Add more
tests.
* NEWS: Mention the new feature.
* spot/twaalgos/forq_contains.hh,
spot/twaalgos/forq_contains.cc (contains_forq): Swap arguments so
they follow the same order as contains().
* tests/python/forq_contains.py: Adjust.