ltlcross: add support for alternating automata

* bin/ltlcross.cc: Add an alternation-removal pass, and
adjust CSV output.
* doc/org/ltlcross.org: Update.
* tests/core/ltl3dra.test, tests/core/ltl3ba.test: Add more tests.
* tests/Makefile.am: Add tests/core/ltl3ba.test.
* NEWS: Mention it.

tests/core/ltl3ba.test

@@ -0,0 +1,42 @@
+#!/bin/sh
+# -*- coding: utf-8 -*-
+# Copyright (C) 2016 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/>.
+
+# Do some quick translations to make sure the neverclaims produced by
+# spot actually look correct!  We do that by parsing them via ltlcross.
+# ltl2neverclaim-lbtt.test does the same with LBTT if it is installed.
+
+. ./defs
+set -e
+
+# Skip this test if ltl3dra is not installed.
+(ltl3ba -v) || exit 77
+
+# The -H1 option will output alternating automata, so this tests
+# ltlcross's support in this area.
+randltl -n 30 2 |
+ltlcross 'ltl3ba -H1' 'ltl3ba -H2' 'ltl3ba -H3' \
+         --ambiguous --strength --csv=output.csv
+
+# Make sure all lines in output.csv have the same number of comas
+sed 's/[^,]//g' <output.csv |
+( read first
+while read l; do
+  test "x$first" = "x$l" || exit 1
+done)