Fixes#282.
* spot/misc/bddlt.hh (bdd_less_than_stable): New function.
* spot/twa/twagraph.cc (merge_edges): Use it.
* tests/core/genltl.test: Adjust, and add an extra test
for the behavior of #282.
* tests/core/complement.test, tests/core/degenid.test,
tests/core/ltldo.test, tests/core/prodor.test,
tests/core/readsave.test, tests/core/sbacc.test,
tests/python/atva16-fig2a.ipynb, tests/python/automata.ipynb,
tests/python/decompose.ipynb, tests/python/dualize.py,
tests/python/highlighting.ipynb, tests/python/piperead.ipynb,
tests/python/product.ipynb, tests/python/simstate.py,
tests/python/tra2tba.py: Adjust all expected outputs.
* NEWS: Mention the bug.
Fixes#262 again. Reported by Maximilien Colange.
* spot/twaalgos/simulation.cc: Use state numbers to order classes, not
their signatures. The problem was that even if two simulation of the
same automaton assign the same signature, the BDD identifier used for
that signature might be different, and therefore the ordering obtained
by using BDDs as keys in a map can be different. A side-effect of
this change is that the order of states in automata produced by
simulation-based reduction may change; many tests had to be updated.
* tests/core/ltl2tgba.test: Add a new test case based on Maximilien's
report.
* tests/core/complement.test, tests/core/det.test,
tests/core/parseaut.test, tests/core/prodor.test, tests/core/scc.test,
tests/python/atva16-fig2a.ipynb, tests/python/automata.ipynb,
tests/python/decompose.ipynb, tests/python/decompose_scc.py,
tests/python/highlighting.ipynb, tests/python/piperead.ipynb,
tests/python/sccinfo.py, tests/python/simstate.py,
tests/python/testingaut.ipynb, tests/python/word.ipynb: Update
test case for new order of states.
