python: export the sbacc() algorithm

Fixes #274.

* python/spot/impl.i: Bind sbacc().
* tests/python/sbacc.py: New tesat.
* tests/Makefile.am: Add sbacc.py.

tests/Makefile.am

@@ -360,6 +360,7 @@ TESTS_python = \
   python/relabel.py \
   python/remfin.py \
   python/satmin.py \
+  python/sbacc.py \
   python/sccfilter.py \
   python/sccinfo.py \
   python/setacc.py \

tests/python/sbacc.py

@@ -0,0 +1,26 @@
+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2017 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
+aut = spot.translate('GFa')
+assert aut.num_states() == 1
+assert not aut.prop_state_acc().is_true()
+aut = spot.sbacc(aut)
+assert aut.num_states() == 2
+assert aut.prop_state_acc().is_true()