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/unop.hh

@@ -0,0 +1,78 @@
+// 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.
+
+/// \file ltlast/unop.hh
+/// \brief LTL unary operators
+#ifndef SPOT_LTLAST_UNOP_HH
+# define SPOT_LTLAST_UNOP_HH
+
+#include <map>
+#include "refformula.hh"
+
+namespace spot
+{
+  namespace ltl
+  {
+
+    /// \brief Unary operators.
+    /// \ingroup ltl_ast
+    class unop : public ref_formula
+    {
+    public:
+      enum type { Not, X, F, G };
+
+      /// Build an unary operator with operation \a op and
+      /// child \a child.
+      static unop* instance(type op, formula* child);
+
+      virtual void accept(visitor& v);
+      virtual void accept(const_visitor& v) const;
+
+      /// Get the sole operand of this operator.
+      const formula* child() const;
+      /// Get the sole operand of this operator.
+      formula* child();
+
+      /// Get the type of this operator.
+      type op() const;
+      /// Get the type of this operator, as a string.
+      const char* op_name() const;
+
+      /// Number of instantiated unary operators.  For debugging.
+      static unsigned instance_count();
+
+    protected:
+      typedef std::pair<type, formula*> pair;
+      typedef std::map<pair, formula*> map;
+      static map instances;
+
+      unop(type op, formula* child);
+      virtual ~unop();
+
+    private:
+      type op_;
+      formula* child_;
+    };
+
+  }
+}
+
+#endif // SPOT_LTLAST_UNOP_HH