Added Geo/CellCompelex.cpp and Geo/CellComplex.h

They construct a cell complex of a finite elemement mesh of a model,
and are able to reduce and coreduce it in order to compute model's
homology groups.

Also added contrib/kbipack to by Saku Suuriniemi for future use to
compute Smith normal forms of the boundary operator matrices of the
reduced cell complex.

Modified Makefiles and configure.in accordingly.