This patch is mostly focused on tagging most virtual methods that
override as such. I found a few methods that where not meant to be
virtual this way, and tagged a few classes "final" along the way.
* bin/common_output.cc, spot/kripke/fairkripke.hh,
spot/kripke/kripke.hh, spot/kripke/kripkegraph.hh,
spot/ltsmin/ltsmin.cc, spot/misc/formater.hh, spot/priv/bddalloc.hh,
spot/ta/ta.hh, spot/ta/taexplicit.hh, spot/ta/taproduct.hh,
spot/ta/tgta.hh, spot/ta/tgtaexplicit.cc, spot/ta/tgtaexplicit.hh,
spot/ta/tgtaproduct.hh, spot/taalgos/emptinessta.hh, spot/tl/declenv.hh,
spot/tl/defaultenv.hh, spot/tl/randomltl.hh, spot/tl/relabel.cc,
spot/twa/bdddict.cc, spot/twa/taatgba.hh, spot/twa/twagraph.hh,
spot/twa/twaproduct.hh, spot/twaalgos/gtec/ce.cc,
spot/twaalgos/gtec/ce.hh, spot/twaalgos/gtec/gtec.hh,
spot/twaalgos/gv04.cc, spot/twaalgos/ltl2taa.cc, spot/twaalgos/magic.cc,
spot/twaalgos/minimize.cc, spot/twaalgos/ndfs_result.hxx,
spot/twaalgos/reachiter.hh, spot/twaalgos/se05.cc,
spot/twaalgos/stutter.cc, spot/twaalgos/tau03.cc: Add more override and
final keywords.
* spot/ltsmin/ltsmin.hh, spot/ltsmin/ltsmin.cc: Expose more of the
ltsmin interface.
* python/spot/ltsmin.i: Add some helper functions on top of this
new interface.
* tests/python/ltsmin.ipynb: Test them.
* NEWS: Mention it.
* spot/ltsmin/ltsmin.cc, spot/ltsmin/ltsmin.hh: Split load_ltsmin() into
ltsmin_model::load() and ltsmin_model::kripke(). Report errors using
exceptions instead of on std::cerr.
* python/spot/ltsmin.i: Deal with exceptions.
* tests/ltsmin/modelcheck.cc, tests/python/ltsmin.ipynb: Adjust.
