This fixes#452, and also fix a bug related to transiant SCCs
incorrectly merged in cosimulation: the source of the edges was
updated without fixing the chaining of the edges.
* spot/twaalgos/simulation.cc: Fix all the above.
* tests/python/simstate.py: Add test case from issue #452.
* tests/core/det.test, tests/core/ltlsynt.test,
tests/core/satmin.test: Lower expected sizes.
* tests/python/decompose.ipynb: Adjust for changed order.