Introduce some experimental kripke classes to simplify writing

interfaces.

* src/kripke/Makefile.am, src/kripke/fairkripke.cc,
src/kripke/fairkripke.hh, src/kripke/kripke.cc,
src/kripke/kripke.hh: New files.
* src/Makefile.am: Recurse into kripke and link libkripke.la.
* configure.ac: Output src/kripke/Makefile.

src/kripke/kripke.cc

@@ -0,0 +1,42 @@
+// Copyright (C) 2009 Laboratoire de Recherche et Developpement 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 2 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 Spot; see the file COPYING.  If not, write to the Free
+// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+// 02111-1307, USA.
+
+#include "kripke.hh"
+
+namespace spot
+{
+
+  bdd kripke::acceptance_conditions_of_state(const state*) const
+  {
+    // There is no acceptance conditions.
+    return bddfalse;
+  }
+
+  bdd kripke::all_acceptance_conditions() const
+  {
+    // There is no acceptance conditions.
+    return bddfalse;
+  }
+
+  bdd kripke::neg_acceptance_conditions() const
+  {
+    return bddtrue;
+  }
+
+}