cleaned/simplified Sign.read_typ, Thm.read_cterm etc.; removed dead code;
cleaned/simplified Sign.read_typ, Thm.read_cterm etc.;
removed dead code;

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