cleaned sig; removed add_defns (now in drule.ML as add_defs); removed add_sigclass; minor internal changes;
cleaned sig;
removed add_defns (now in drule.ML as add_defs);
removed add_sigclass;
minor internal changes;

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