Functions include:
* glm_mat#x#_copy
* glm_mat#x#_zero
* glm_mat#x#_mul
* glm_mat#x#_mulv
* glm_mat#x#_transpose
* glm_mat#x#_scale
Commit also includes some minor changes to
* mat2
* mat3
* mat4
Signed-off-by: Vincent Davis Jr <vince@underview.tech>