Added a column-major graphics demo

[ZERICO2005]

Based off the graphx buffered cube example

Uses code from graphy so vsync is properly handled and etc

I got errors from the org keyword used in gfy_FillScreen, so I've implemented it in C with memset instead for now.

[calc84maniac]

I'm not really a fan of the assembly usage in a C example, especially reimplementing stuff from GraphX that could be done just the same by using functions directly from GraphX. The only "unique" thing in the assembly code is the set pixel function, and that could just as easily be done in C (or the line draw functions could be changed to use pointer arithmetic if speed is an issue, as long as clipping isn't needed).

[ZERICO2005]

I was not sure how to implement vsync in C, so I reused graphx/graphy functions for it. The purpose for this demo is to show how there is no diagonal screen tearing in column major mode

[calc84maniac]

The point is that you shouldn't reuse graphx functions, this is a library demo so just call gfx functions directly