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.
a66e7704d8