added Task_Queue.depend (again) -- light-weight version for transitive graph; Future.join_results: record explicit dependency, detect direct task-task join cycles; Future.join_results: no change of interruptibility, allows to interrupt wait; added Future.worker_task; ThyInfo.schedule_futures: uninterruptible outer join;

handle Pattern.MATCH, not arbitrary exceptions; misc tuning, trying to reduce line length a bit;