tl: mp_class() and --format=%[vw]h

Tools for deciding the class of a formula.

* spot/tl/hierarchy.cc, spot/tl/hierarchy.hh: New files.
* spot/tl/Makefile.am: Add them.
* bin/common_output.cc, bin/common_output.hh: Implement --format=%h.
* tests/core/hierarchy.test: More tests.
* NEWS: Update.

spot/tl/hierarchy.hh

@@ -0,0 +1,40 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2017 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/>.
+
+#pragma once
+
+#include <spot/tl/formula.hh>
+
+namespace spot
+{
+  /// \brief Return the class of \a f in the temporal hierarchy of Manna
+  /// and Pnueli (PODC'90).
+  ///
+  /// The class is indicated using a character among:
+  /// - 'B' (bottom) safety properties that are also guarantee properties
+  /// - 'G' guarantee properties that are not also safety properties
+  /// - 'S' safety properties that are not also guarantee properties
+  /// - 'O' obligation properties that are not safety or guarantee
+  ///       properties
+  /// - 'P' persistence properties that are not obligations
+  /// - 'R' recurrence properties that are not obligations
+  /// - 'T' (top) properties that are not persistence or recurrence
+  ///   properties
+  SPOT_API char mp_class(formula f);
+}