Greatly improve shading model

- Directional toon lighting component on entities. (extension of the
shadow light source)
The shadows were doing this anyways, but with extremely bad
stairstepping. Now it smoothly blends into the shadow.
- Greatly reduce shadow acne via the above and a larger bias.
- Respect culling mode for each model.
- Two sided shading for course models.
- Disable alpha for water that does not use it.
- Only GBA Sky Garden's skybox receives shadows now.
- Custom light positions for some maps. (you can guess which)

code/particles/nitroParticle.js

@@ -199,6 +199,7 @@ window.NitroParticle = function(scene, emitter, pos, vel, dir, dirVel, duration,
             nitroRender.last.obj = obj;
         }
 
+        gl.disable(gl.CULL_FACE);
         gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
 
         nitroRender.setColMult([1, 1, 1, 1]);