Subdivided cubes, colored AABBs, some more

* Subdivided cubes
- The cubes' sides are now subdivided in the same way as the surfaces
* Colored AABBs
- The AABBs are now color-coded. All different kind of objects have
their own color: regular shapes are red, interactive objects are yellow,
moving scene are blue, power ups are green and disabled shapes (the ones
that ODE are currently ignoring) are grey/whiteish.
* Auto-disabling bodies
- Made ODE ignore objects that aren't moving and that aren't likely to
interact with other enabled objects.
* Tried to fix moving platforms
- There is still a problem with the friction of the moving platforms. I
tried to fix it, but didn't get anywhere...