Merge pull request #428 from jankoboehm/spielwiese

Fix for Cygwin: cast to pointer from integer of different size
chg: simplified npNegM
chg: new version of oldpolymake.lib from Thomas Markwig (keilen@mathematik.uni-kl.de)
fix: loading of polymake.so in oldpolymake.lib
fix: oldpolymake.lib bigintmat <-> intmat issues
chg: trying up oldpolymake.lib

    - renamed procedures that conflicted with procedures in polymake.so
    - fixed remaining mistakes in library due to bigintmats where previously only intmats were expected
    - renamed it back to polymake.lib

    the rename to oldpolymake.lib only happened because initially it was planned to call the polymake kernel interface polymake.lib, since it is easier for the users to not distinguish between interpreter libraries and shared objects and due to a misconception that polymake.lib was a pure interface to polymake. Since both proved to be wrong, I decided to undo the name change.