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/lib/raise.c

@@ -0,0 +1,81 @@
+/* Provide a non-threads replacement for the POSIX raise function.
+
+   Copyright (C) 2002-2003, 2005-2006, 2009-2017 Free Software Foundation, Inc.
+
+   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/>.  */
+
+/* written by Jim Meyering and Bruno Haible */
+
+#include <config.h>
+
+/* Specification.  */
+#include <signal.h>
+
+#if HAVE_RAISE
+/* Native Windows platform.  */
+
+# include <errno.h>
+
+# if HAVE_MSVC_INVALID_PARAMETER_HANDLER
+#  include "msvc-inval.h"
+# endif
+
+# undef raise
+
+# if HAVE_MSVC_INVALID_PARAMETER_HANDLER
+static int
+raise_nothrow (int sig)
+{
+  int result;
+
+  TRY_MSVC_INVAL
+    {
+      result = raise (sig);
+    }
+  CATCH_MSVC_INVAL
+    {
+      result = -1;
+      errno = EINVAL;
+    }
+  DONE_MSVC_INVAL;
+
+  return result;
+}
+# else
+#  define raise_nothrow raise
+# endif
+
+#else
+/* An old Unix platform.  */
+
+# include <unistd.h>
+
+# define rpl_raise raise
+
+#endif
+
+int
+rpl_raise (int sig)
+{
+#if GNULIB_defined_signal_blocking && GNULIB_defined_SIGPIPE
+  if (sig == SIGPIPE)
+    return _gl_raise_SIGPIPE ();
+#endif
+
+#if HAVE_RAISE
+  return raise_nothrow (sig);
+#else
+  return kill (getpid (), sig);
+#endif
+}