MeshDrawer renamed Renderer to remove confusion with Drawer
Got some sort of environment mapping for ambiant lighting.
Put walls and ceilings back in.
Make lists of everything to draw before drawing them, handy for walls.
Better variable and function names in main.
Render close walls first to reduce fill rate.
Cleaning buffer code in preparation to uniform buffer for lights.
Minor cleaning.
Camera UBO now managed like the other buffers, paving the way for Light UBO.