* spot/twaalgos/sccinfo.cc, spot/twaalgos/sccinfo.hh: Make sure
scc_and_mark_filter does not install a filter if there is nothing
to filter.
* tests/python/genem.py, spot/twaalgos/genem.cc,
python/spot/impl.i: Adjust.
* spot/twaalgos/sccinfo.hh, python/spot/impl.i: Here. This avoid
ambiguities where options (integer in Python) are interpreted as
initial states.
* tests/python/genem.py: Adjust.
* spot/twaalgos/sccinfo.hh, spot/twaalgos/sccinfo.cc: Here.
* spot/twaalgos/genem.cc: Use it.
* python/spot/impl.i, python/spot/__init__.py: Add bindings.
* tests/python/genem.py: Test it.
* NEWS: Mention it.
* tests/python/genem.py: Use SPOT_ON_ACC explicitely.
* spot/twaalgos/genem.cc: Do not keep track of states. Don't
check that the clauses of the disjuncts are Fin-less: they aren't
(this was discovered while discussing with Jan and Fanda).
Implement an accepting run search in spot::sccinfo, use it with the
generic emptiness check.
* spot/twaalgos/sccinfo.cc, spot/twaalgos/sccinfo.hh: Here.
* spot/twaalgos/genem.cc, spot/twaalgos/genem.hh: Use it.
* tests/python/genem.py: Test it.
Fixes#360.
* spot/twa/acc.cc, spot/twa/acc.hh (force_inf): New method.
* spot/twaalgos/genem.cc: Fix the emptiness check using force_inf.
* tests/python/genem.py: Add test case and adjust the python
version of the emptiness check.
* spot/twa/acc.cc, spot/twa/acc.hh (fin_unit, one_fin): New function.
* spot/twaalgos/genem.cc, spot/twaalgos/genem.hh: New files.
* spot/twaalgos/Makefile.am: Add it.
* tests/python/genem.py: New file.
* tests/Makefile.am: Add it.
* python/spot/impl.i: Add bindings for genem.hh.
* NEWS: Mention the new function.
