implement NCSB complementation

* spot/twaalgos/isdet.cc,spot/twaalgos/isdet.hh: Two new functions to
highlight deterministic SCCs
* spot/twaalgos/complement.cc,spot/twaalgos/complement.hh:
Implementation of the NCSB complementation algorithm
* tests/Makefile.am, tests/python/complement_semidet.py: Test the
implementation
* NEWS: document function

tests/python/complement_semidet.py

@@ -0,0 +1,38 @@
+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2018 Laboratoire de Recherche et Développement de
+# l'Epita (LRDE).
+#
+# This file is part of Spot, a model checking library.
+#
+# Spot is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# Spot is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import spot
+import buddy
+
+
+def complement(aut):
+    return spot.dualize(aut.postprocess('det', 'gen'))
+
+
+n = 10000
+
+for aut in spot.automata(
+        "randltl -n-1 a b "
+        "| ltl2tgba "
+        "| autfilt --is-semi-deterministic --acceptance-is=Buchi -n{} |"
+        .format(n)):
+
+    comp = complement(aut)
+    semidet_comp = spot.complement_semidet(aut, True)
+    assert(comp.equivalent_to(semidet_comp))