Cube with diagonal up

This is a version of the cube from figures 1.10, 1.12, 3.4, 3.7 and 3.8 of [Visualizing Mathematics with 3D Printing](http://3dprintmath.com), with owens' breakaway base design added, so that it can be printed with the long diagonal of the cube upwards. You should print with support, since the base is not quite flat on the bottom, but the design should not require support reaching up to the cube.