Added some basic geometric primitives such as planes, rays, segments
and lines (plus some extra functions like xProject, xBarycentric, Lerpf),
as well as some intersection tests between them.
Additionally, I split massive math test into smaller ones and tweaked
unit test library (testing no longer stops after first failure).
After some testing, I decided to ditch the DirectX approach of writing
math functions.
Additionally, I added unit tests (with reference wxMaxima calculations)
for most math functions and fixed several bugs along the way.
