rename safety.hh as strength.hh

* src/twaalgos/safety.cc, src/twaalgos/safety.hh: Rename as ...
* src/twaalgos/strength.cc, src/twaalgos/strength.hh: ... these.
* src/bin/ltlfilt.cc, src/tests/ikwiad.cc, src/twaalgos/Makefile.am,
src/twaalgos/compsusp.cc, src/twaalgos/minimize.cc,
wrap/python/spot_impl.i: Adjust.

src/twaalgos/strength.hh

@@ -0,0 +1,49 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2010, 2011, 2013, 2014, 2015 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 "sccinfo.hh"
+
+namespace spot
+{
+  /// \brief Whether an automaton is terminal.
+  ///
+  /// An automaton is terminal if any accepting path ends on an
+  /// accepting state with only one transition that is a self-loop
+  /// labelled by true.
+  ///
+  /// \param aut the automaton to check
+  ///
+  /// \param sm an scc_info object for the automaton if available (it
+  /// will be built otherwise).
+  SPOT_API bool
+  is_terminal_automaton(const const_twa_graph_ptr& aut, scc_info* sm = nullptr);
+
+  /// \brief Whether a minimized WDBA represents a safety property.
+  ///
+  /// A minimized WDBA (as returned by a successful run of
+  /// minimize_obligation()) represent safety property if it contains
+  /// only accepting transitions.
+  ///
+  /// \param aut the automaton to check
+  SPOT_API bool
+  is_safety_mwdba(const const_twa_graph_ptr& aut);
+
+}