Further fix for $_SESSION being empty when used with XTemplate::scan_globals() - monitor & feedback if you experience side-effects * Added XTemplate::comment_delim defaults to '#' * Added XTemplate::callback_delim defaults to '|' * Tag callback functions - improve security (thanks Oliver): * Added XTemplate::allow_callbacks property (boolean) to allow switching functionality off * Added XTemplate::allowed_callbacks (array) to limit functions available from templates * Callbacks now only available for methods of subclasses of XTemplate or as functions in XTemplate::allowed_callbacks array