Fixed bugs regarding level borders and the camera in editor mode.
Implemented a variant of the phong shader without the specular highlight
for testing purposes. It's used as a sort of lantern that follows the
player and it's illuminating the world. However, flaws in the primitive
renderer are becoming obvious now as the layers scale has to be worked
around to distribute the illumination correctly and the entities
themselves are not affected by the lantern movement. It's time to revise
the design of the renderer now.