changed is_base to find point cuts; fixed cross table generation when matrix is sparse
changed is_base to find point cuts; fixed cross table generation when matrix is sparse

will need to redefine "is_base" and whole implicit dimension thing

zejn/cubes,jell0720/cubes,noyeitan/cubes,ubreddy/cubes,pombredanne/cubes,jell0720/cubes,jell0720/cubes,ubreddy/cubes,zejn/cubes,noyeitan/cubes,pombredanne/cubes,pombredanne/cubes,she11c0de/cubes,ubreddy/cubes,she11c0de/cubes,cesarmarinhorj/cubes,zejn/cubes,she11c0de/cubes,noyeitan/cubes,cesarmarinhorj/cubes,cesarmarinhorj/cubes