added fsub.thy (poplmark challenge) to the examples
directory.
@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/}}}
@misc{mathpartir,author={Didier R\'emy},title={mathpartir},
note={\url{http://cristal.inria.fr/~remy/latex/}}}
@misc{tar,author={Gerwin Klein and Norber Schirmer and Tobias Nipkow},
title={{LaTeX} sugar theories and support files},
note={\url{http://isabelle.in.tum.de/sugar.tar.gz}}}