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.
Reported by Thibaud Michaud
* spot/twaalgos/sbacc.cc: Do not label rejecting SCCs with the empty
mark, as it might be accepting.
* tests/core/sbacc.test: Add test cases.
* NEWS: Mention the bug.
Fixes#241.
* spot/twaalgos/postproc.cc: Use the deterministic monitor if it
has as many states as the non-deterministic one.
* spot/twaalgos/minimize.cc (minimize_monitor): Quickly check
for terminal automata.
* spot/twaalgos/stripacc.cc: Set the weak property.
* spot/twaalgos/stripacc.hh: Improve documentation.
* tests/core/monitor.test, tests/core/sbacc.test: Update.
* NEWS: Mention the issue.
* spot/twaalgos/sbacc.cc: Do not assign to one_in twice, and
fix the value of init_acc.
* tests/core/sbacc.test: Add a test case.
* NEWS: Mention the bug.
