* spot/twaalgos/gfguarantee.cc: Combine the last letter read
with the first one of the next pass when doing transition-based
acceptance. Also move the initial states to the source of any
accepting transition if the input is deterministic.
* tests/core/ltl2tgba2.test, tests/core/satmin.test,
tests/python/stutter-inv.ipynb: Reduce expected sizes of a few
automata.