Added functions for fol_type; also put some functions to the signature, used by ResHolClause.
Added functions for fol_type; also put some functions to the signature, used by ResHolClause.

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