It looks horrible due to the lack of lighting etc, but it's good enough
for basic testing, especially of my render job design (that passed with
flying colors).
This allows the use of an entity id to index into the entity data and
fetch the transform and colormod data in the vertex shader, thus making
instanced rendering possible. Non-world brush entities are still not
rendered, but the world entity is using both the entity data buffer and
entid buffer.
