rem: cbs->callback( T, msg );
add: cbs->callback( trans, msg );
context: void callback_event( tmcb_type cbt , struct sip_msg *msg ){	struct tm_callback_s *cbs;	DBG("DBG: callback type %d entered\n", cbt );	for (cbs=callback_array[ cbt ]; cbs; cbs=cbs->next)  {		DBG("DBG: callback id %d entered\n", cbs->id );		cbs->callback( T, msg );	}}