* spot/twaalgos/cleanacc.cc: Use cleanup_acceptance if
propagate_fin_inf was useful.
* spot/twa/acc.hh: Avoid to reverse the order of the condition in
propagate_fin_inf.
* tests/core/accsimpl.test, tests/core/remfin.test,
tests/python/merge.py, tests/python/automata.ipynb: Update tests.
* tests/python/toparity.py: Update tests and add tests to check the
number of states.
Fixes#315.
* spot/twaalgos/cleanacc.cc (simplify_acceptance_here): Do not
compare the first edge against previous_a.
* tests/core/accsimpl.test: New file.
* tests/Makefile.am: Add it.
* NEWS: Mention the bug.