renamed Drule.add/del/merge_rules to Thm.add/del/merge_thms; tuned;
renamed Drule.add/del/merge_rules to Thm.add/del/merge_thms;
tuned;

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle