mat3 matrix, custom int typedefs, more tests.

Created mat3 matrix for 2d vector manipulations. Removed the array from
the vec definitions and changed them to standard structs because I
didn't seem to need it. Changed to using my own int typedefs, just to
get rid of the need for stdint.h. Added my own sqrt function. Added more
tests for math functions, and vec3s and vec4s.