Merge the core and python tests in the tests/ directory

* tests/: Rename as...
* tests/core/: ... this.
* python/tests/: Rename as...
* tests/python/: ... this.
* python/tests/run.in: Move as...
* tests/run.in: This, and adjust.
* tests/Makefile.am: Adjust to run both core and python tests.
* configure.ac, README, debian/python3-spot.examples, debian/rules,
doc/org/tut.org, python/Makefile.am, spot/ltsmin/Makefile.am,
spot/ltsmin/kripke.test, spot/sanity/ipynb.test: Adjust.

tests/run.in

@@ -0,0 +1,86 @@
+#!/bin/sh
+# -*- coding: utf-8 -*-
+# Copyright (C) 2010, 2011, 2014, 2015 Laboratoire de Recherche et
+# Developpement de l'EPITA (LRDE).
+# 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 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/>.
+
+# Darwin needs some help in figuring out where non-installed libtool
+# libraries are (on this platform libtool encodes the expected final
+# path of dependent libraries in each library).
+modpath='@abs_top_builddir@/python/.libs'
+modpath=$modpath:'@top_builddir@/spot/.libs':'@top_builddir@/buddy/spot/.libs'
+
+# We need access to both the *.py files, and the *.so.  We used to
+# rely on a module called ltihooks.py to teach the import function how
+# to load a Libtool library, but it started to cause issues with
+# Python 2.6.
+pypath='@abs_top_builddir@/python':'@abs_top_builddir@/python/.libs'
+pypath=$pypath:'@abs_top_srcdir@/python':'@abs_top_srcdir@/python/.libs'
+
+PATH="@abs_top_builddir@/bin:$PATH"
+export PATH
+
+test -z "$1" &&
+    PYTHONPATH=$pypath DYLD_LIBRARY_PATH=$modpath exec @PYTHON@
+srcdir="@srcdir@"
+
+case $1 in
+    */*)
+	dir=${1%/*}
+	dir=${dir##*/}
+	mkdir -p $dir
+	cd $dir
+	case $1 in
+	    ../*)
+		base=../$1
+		;;
+	    [\\/$]* | ?:[\\/]* )
+		base=$1
+		;;
+	    *)
+		base=${1##*/}
+		;;
+	esac
+
+	test $srcdir != '.' && srcdir="@abs_srcdir@/$dir"
+        shift
+        set x "$base" "$@"
+	shift
+	;;
+esac
+
+export srcdir
+
+case $1 in
+  *.ipynb)
+    PYTHONPATH=$pypath DYLD_LIBRARY_PATH=$modpath \
+    exec $PREFIXCMD @PYTHON@ @abs_srcdir@/python/ipnbdoctest.py "$@";;
+  *.py)
+    PYTHONPATH=$pypath DYLD_LIBRARY_PATH=$modpath \
+    exec $PREFIXCMD @PYTHON@ "$@";;
+  *.test)
+    exec sh -x "$@";;
+  *python*)
+    PYTHONPATH=$pypath DYLD_LIBRARY_PATH=$modpath \
+    exec $PREFIXCMD "$@";;
+  *)
+    echo "Unknown extension" >&2
+    exit 2;;
+esac