[ODE] Flat cylinder geom come to life!

[Alen Ladavac]

>      So there are no cylinder vs plane in Croteam's side. (Am I right
>      Alen ???).

Yes, you are right. Plane is a very degenerate piece of geometry, which is
not very useful in a game, only as floor in test scenes. So we've spared
ourselves one count of N in the NxN collider matrix, by just puting a large
box for floor in test scenes. :)

It should be fairly easy to model it by just stripping a box-cylinder
collider off all axes except for the top face.

Cheers,
Alen