added store_thms etc. (formerly in Thy/thm_database.ML); added bind_thm(s) (formerly in old_goals.ML); adapted to Context.thread_data interface; removed obsolete get/set_context; renamed ML_Context.>> to Context.>> (again);

adapted to Context.thread_data interface;

moved bind_thm(s) to ML/ml_context.ML; removed obsolete Thy/thm_database.ML (cf. ML/ml_context.ML);