New wesnoth-defaults utility script

I wrote this a long time ago and have been using it to ease testing of
Wesnoth's default configuration under different conditions ever since.

It creates a new configuration and data directory under /tmp that only
exists for the duration of the Wesnoth session, and disables WML cache
functionality.

This is extremely useful for quickly testing and debugging functionality
dependant on user configuration settings.

utils/wesnoth-defaults

@@ -0,0 +1,47 @@
+#!/bin/sh
+#
+# Runs Wesnoth using a clean, throwaway config directory.
+#
+# The configuration directory is created on your temporary
+# directory (i.e. /tmp) with a unique name every time, and
+# deleted when finished.
+#
+# Usage:
+#     wesnoth-defaults <command line>
+#
+# Examples:
+#     wesnoth-defaults ~/src/wesnoth-1.12/wesnoth
+#     wesnoth-defaults ~/src/wesnoth-1.12/wesnoth -s server.wesnoth.org
+#     wesnoth-defaults ~/src/wesnoth-trunk/wesnoth-debug --campaign Heir_To_The_Throne
+#
+
+SELF=`basename $0`
+
+do_error()
+{
+	echo "$SELF: $*" 1>&2
+}
+
+if [ -z $1 ]; then
+	do_error "You must specify a command line to run!"
+	exit 1
+fi
+
+WESNOTH_BIN_PATH=$1
+TEMP_CONFIG_DIR=`mktemp -qd`
+
+if [ -z $TEMP_CONFIG_DIR ]; then
+	do_error "Could not create temporary dir before launch!"
+	exit 2
+fi
+
+do_cleanup()
+{
+	rm -rf $TEMP_CONFIG_DIR || do_error "Could not remove temporary config dir"
+}
+
+trap do_cleanup INT QUIT HUP TERM EXIT
+
+shift
+
+$WESNOTH_BIN_PATH --nocache --userdata-dir $TEMP_CONFIG_DIR --userconfig-dir $TEMP_CONFIG_DIR $@