Add a visitor to relabel the atomic proposition in formulas.

* src/ltlvisit/relabel.cc, src/ltlvisit/relabel.hh: New files.
* src/ltlvisit/Makefile.am: Add them.
* src/ltlvisit/clone.cc (recurse): Don't call clone(), nobody
needs that.  Instead, really recurse.
* src/bin/ltlfilt.cc: Add a --relabel option.
* src/bin/genltl.cc: Relabel formulas if --lbt is used.
* src/sanity/style.test: Tweak detection of i++.

src/ltlvisit/relabel.hh

@@ -0,0 +1,42 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2012 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 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.
+
+#ifndef SPOT_LTLVISIT_RELABEL_HH
+# define SPOT_LTLVISIT_RELABEL_HH
+
+#include <ltlast/formula.hh>
+
+namespace spot
+{
+  namespace ltl
+  {
+    enum relabeling_style { Abc, Pnn };
+
+    /// \brief Relabel the atomic proposition in a formula.
+    ///
+    /// \ingroup ltl_rewriting
+    const formula* relabel(const formula* f, relabeling_style style);
+  }
+}
+
+
+
+#endif // SPOT_LTLVISIT_RELABEL_HH