fix Python bindings for relabeling_map, and document them

This fixes #61, and addresses one item of #14.

* src/ltlvisit/relabel.hh: Use a map rather than a unordered_map,
because the Swig binding for unordered_map do not seem functional.
* wrap/python/spot_impl.i: Adjust.
* wrap/python/tests/relabel.py: New file.
* wrap/python/tests/Makefile.am: Add it.
* doc/org/tut02.org: New file.
* doc/Makefile.am: Add it.

wrap/python/tests/Makefile.am

@@ -49,5 +49,6 @@ TESTS = \
   piperead.ipynb \
   randaut.ipynb \
   randltl.ipynb \
+  relabel.py \
   setxor.py \
   testingaut.ipynb

wrap/python/tests/relabel.py

@@ -0,0 +1,32 @@
+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2015  Laboratoire de Recherche et Développement
+# de l'Epita
+#
+# 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/>.
+
+import spot
+
+f = spot.formula('GF(a & b) -> (FG(a & b) & Gc)')
+m = spot.relabeling_map()
+g = spot.relabel_bse(f, spot.Pnn, m)
+res = ""
+for old, new in m.items():
+    res += "#define {} {}\n".format(old, new)
+res += str(g)
+print(res)
+assert(res == """#define p0 a & b
+#define p1 c
+GFp0 -> (FGp0 & Gp1)""")