Reduce the amount of uncolored transitions
after split_2step by trying to color the env transitions.
This is currently only supported for parity like
acceptance conditions.
* spot/twaalgos/game.cc: Determinizatio of "colored"
game can created trivial self-loops. Fix them
* spot/twaalgos/synthesis.cc: Here
* tests/core/ltlsynt.test,
tests/python/_synthesis.ipynb,
tests/python/games.ipynb,
tests/python/synthesis.ipynb,
tests/python/synthesis.py: New and adjusted tests
524edea8da