Revert everything related to Damien's work in 2008 (he will commit a new version soon).

Here are the reverted patches:
8c0d1003b0,
25a3114287,
9afbaf6342,
dc0005f4e1,
543190f2bc.

src/ltlast/refformula.cc

@@ -0,0 +1,58 @@
+// Copyright (C) 2003, 2004  Laboratoire d'Informatique de Paris 6 (LIP6),
+// département Systèmes Répartis Coopératifs (SRC), Université Pierre
+// et Marie Curie.
+//
+// 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 "refformula.hh"
+#include <cassert>
+
+namespace spot
+{
+  namespace ltl
+  {
+    ref_formula::ref_formula()
+      : ref_counter_(0)
+    {
+    }
+
+    ref_formula::~ref_formula()
+    {
+    }
+
+    void
+    ref_formula::ref_()
+    {
+      ++ref_counter_;
+    }
+
+    bool
+    ref_formula::unref_()
+    {
+      assert(ref_counter_ > 0);
+      return !--ref_counter_;
+    }
+
+    unsigned
+    ref_formula::ref_count_()
+    {
+      return ref_counter_;
+    }
+
+  }
+}