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/ltlcross4.test

@@ -1,88 +0,0 @@
-#!/bin/sh
-# -*- coding: utf-8 -*-
-# Copyright (C) 2012, 2013, 2014 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/>.
-
-. ./defs
-set -e
-
-test -z "$PYTHON" && exit 77
-
-ltl2tgba=../../bin/ltl2tgba
-
-cat >formulas.txt <<EOF
-GFa & GFb
-GFa -> GFb
-EOF
-
-../../bin/ltlcross -F formulas.txt \
-  "{ltl2tgba any} $ltl2tgba --lbtt --any %f > %T" \
-  "{ltl2tgba det} $ltl2tgba --lbtt --deterministic %f > %T" \
-  "{ltl2tgba sma} $ltl2tgba --lbtt --small %f > %T" \
-  --csv=output.csv
-
-cat >test.py <<EOF
-import sys
-try:
-  import pandas
-except ImportError:
-  sys.exit(77)
-
-x = pandas.read_csv("output.csv")
-print(x.filter(('formula', 'tool',
-                'states', 'transitions')).groupby('tool').describe())
-EOF
-
-# will exit 77 if panda is not installed
-$PYTHON test.py >out.1
-
-# remove trailing whitespace from pandas' output,
-# and limit to 26 lines, because Pandas 0.13 adds
-# the size of the dataframe afterwards.
-sed 's/[ \t]*$//g;26q' <out.1 > py.out
-
-cat >expected <<EOF
-                      states  transitions
-tool
-ltl2tgba any count  4.000000     4.000000
-             mean   2.250000    10.000000
-             std    0.957427     5.163978
-             min    1.000000     4.000000
-             25%    1.750000     7.000000
-             50%    2.500000    10.000000
-             75%    3.000000    13.000000
-             max    3.000000    16.000000
-ltl2tgba det count  4.000000     4.000000
-             mean   2.250000     9.250000
-             std    0.957427     4.573474
-             min    1.000000     4.000000
-             25%    1.750000     6.250000
-             50%    2.500000     9.500000
-             75%    3.000000    12.500000
-             max    3.000000    14.000000
-ltl2tgba sma count  4.000000     4.000000
-             mean   2.250000     9.250000
-             std    0.957427     4.573474
-             min    1.000000     4.000000
-             25%    1.750000     6.250000
-             50%    2.500000     9.500000
-             75%    3.000000    12.500000
-             max    3.000000    14.000000
-EOF
-
-diff py.out expected