The file geo.py is really just a group of general purpose functions
and geometry-related functions.
This is probably the two functions that are the most useful,
they move within the matrix, based on the direction of travel.
The following functions get or set the elements in the
matrix. The real cool thing about them, is that if you have an
out-of-bounds value, they print the values to the console, which are a real help
when you are progamming.