translate any automaton to a parity automaton

* spot/twaalgos/toparity.cc, spot/twaalgos/toparity.hh: implement it,
  based on last-appearance record (LAR)
* spot/twaalgos/Makefile.am: build it
* NEWS: document it
* python/spot/impl.i: add to python bindings
* tests/Makefile.am, tests/python/toparity.py: test it

tests/python/toparity.py

@@ -0,0 +1,32 @@
+#!/usr/bin/python3
+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2018 Laboratoire de Recherche et Développement de
+# l'EPITA.
+#
+# 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
+
+for f in spot.randltl(4, 400):
+    d = spot.translate(f, "det", "G")
+    p = spot.to_parity(d)
+    assert spot.are_equivalent(p, d)
+
+for f in spot.randltl(5, 2000):
+    n = spot.translate(f)
+    p = spot.to_parity(n)
+    assert spot.are_equivalent(n, p)
+