* spot/twaalgos/simulation.cc: Restrict common_in marks to current SCC
when pushing them, otherwise weak automata might become inherently
weak.
* tests/core/sim3.test: Add test case.
Suggested by František Blahoudek.
* spot/twaalgos/simulation.cc: When doing forward simulation with
state-based acceptance as input but transition-based acceptance as
output, pull acceptance marks on incoming edges instead of pushing
them to outgoing edges.
* tests/core/dra2dba.test, tests/core/exclusive-tgba.test,
tests/core/ltlcrossce.test, tests/core/satmin3.test,
tests/core/sim3.test, tests/python/satmin.ipynb: Adjust test cases.
* NEWS: Mention the change.
* spot/twaalgos/postproc.cc: Here.
* spot/twaalgos/cobuchi.cc, spot/twaalgos/totgba.cc: Fix some bug
uncovered by the new simplified automata.
* tests/core/satmin2.test, tests/core/sccdot.test,
tests/core/sim3.test, tests/python/decompose.ipynb,
tests/python/satmin.ipynb: Update expected results.
* NEWS: Mention the simplification and the bug.
