dest_ctyp: raise exception for non-constructor;
dest_comb: replaced expensive fastype_of by Term.argument_type;
dest_abs: replaced expensive variant_abs by Term.dest_abs;
hyps: fast_term_ord;
@string{LNCS="Lect.\ Notes in Comp.\ Sci."}
@string{Springer="Springer-Verlag"}
@book{LNCS2283,author={Tobias Nipkow and Lawrence Paulson and Markus Wenzel},
title="Isabelle/HOL --- A Proof Assistant for Higher-Order Logic",
publisher=Springer,series=LNCS,volume=2283,year=2002,
note={\url{http://www.in.tum.de/~nipkow/LNCS2283/}}}