D7: editor multi-cursor support

Add secondary_cursors field to Editor with insert_char_multi,
delete_back_multi, delete_forward_multi methods. Right-to-left
processing ensures position shifts don't corrupt earlier insertions.

7 new tests: add/clear, all_positions, insert, delete_back,
delete_forward, unicode, duplicate-add.

local/recipes/tools/diffutils/source/gnulib-tests/test-exclude7.sh

@@ -0,0 +1,47 @@
+#! /bin/sh
+# Test suite for exclude.
+# Copyright (C) 2009-2017 Free Software Foundation, Inc.
+# This file is part of the GNUlib Library.
+#
+# This program 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.
+#
+# This program 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/>.
+
+. "${srcdir=.}/init.sh"; path_prepend_ .
+fail=0
+
+# Test exclude precedence
+
+cat > in <<EOT
+foo*
+bar
+Baz
+EOT
+
+cat > expected <<EOT
+bar: 0
+bar: 1
+EOT
+
+test-exclude in -include in -- bar > out || exit $?
+test-exclude -include in -no-include in -- bar >> out || exit $?
+
+# Find out how to remove carriage returns from output. Solaris /usr/ucb/tr
+# does not understand '\r'.
+case $(echo r | tr -d '\r') in '') cr='\015';; *) cr='\r';; esac
+
+# normalize output
+LC_ALL=C tr -d "$cr" < out > k && mv k out
+
+compare expected out || fail=1
+
+Exit $fail