[ticket/security/275] Add language vars and proper error codes

SECURITY-275

phpBB/language/en/common.php

@@ -678,6 +678,10 @@ $lang = array_merge($lang, array(
 	'RETURN_TOPIC'				=> '%sReturn to the topic last visited%s',
 	'RETURN_TO'					=> 'Return to “%s”',
 	'RETURN_TO_INDEX'			=> 'Return to Board Index',
+
+	'ROUTE_NOT_FOUND'				=> 'The requested route "%1$s" could not be found.',
+	'ROUTE_INVALID_MISSING_PARAMS'	=> 'Invalid or missing parameters passed for route "%1$s".',
+
 	'FEED'						=> 'Feed',
 	'FEED_NEWS'					=> 'News',
 	'FEED_TOPICS_ACTIVE'		=> 'Active Topics',