Add 3x3 and 3x1 matrix functions
fix some formatting in quat.h
Add vec3_div and vec3_div_self functions
remove update_entity_rotation and rx, ry, rz from struct entity

Not used anymore.
Calculate vertex normals per triangle taking local geometry into account
nuke redundant sng_rand()
fix formatting of sphere_in_frustum()
add shader processing code
add shader code