Introduce some masked tgba.

* src/tgba/tgbamask.cc, src/tgba/tgbamask.hh,
src/tgba/tgbaproxy.cc, src/tgba/tgbaproxy.hh: New files.
* src/tgba/Makefile.am: Add them.
* src/tgbatest/explicit3.cc, src/tgbatest/explicit3.test:
New files.
* src/tgbatest/Makefile.am: Add them.

src/tgbatest/explicit3.test

@@ -0,0 +1,68 @@
+#!/bin/sh
+# Copyright (C) 2013 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/>.
+
+. ./defs
+
+set -e
+
+run 0 ../explicit3 | tee stdout
+cat >expected <<EOF
+digraph G {
+  0 [label="", style=invis, height=0]
+  0 -> 1
+  1 [label="0"]
+  1 -> 2 [label="a\n"]
+  2 [label="1"]
+  2 -> 3 [label="a\n"]
+  2 -> 4 [label="b\n"]
+  3 [label="2"]
+  3 -> 1 [label="a\n"]
+  4 [label="3"]
+  4 -> 5 [label="c\n"]
+  5 [label="4"]
+  5 -> 4 [label="c\n{Acc[b]}"]
+}
+digraph G {
+  0 [label="", style=invis, height=0]
+  0 -> 1
+  1 [label="0"]
+  1 -> 2 [label="a\n"]
+  2 [label="1"]
+  2 -> 3 [label="a\n"]
+  3 [label="2"]
+  3 -> 1 [label="a\n"]
+}
+digraph G {
+  0 [label="", style=invis, height=0]
+  0 -> 1
+  1 [label="0"]
+}
+digraph G {
+  0 [label="", style=invis, height=0]
+  0 -> 1
+  1 [label="1"]
+  1 -> 2 [label="b\n"]
+  2 [label="3"]
+  2 -> 3 [label="c\n"]
+  3 [label="4"]
+  3 -> 2 [label="c\n{Acc[b]}"]
+}
+EOF
+
+cmp expected stdout