[ODE] Simple FPS-like character

[Morgan McGuire]

> I've been using ODE for years now, but i'm still amazed at the 
> lack of support for simple characters collision detection/

I use a capsule, but also float the capsule slightly above the ground to allow
thin characters to climb steep stairs.  I do this by casting a ray downwards
(via ODE's collision detection) to find the ground and then applying an upwards
force if the capsule is too close to the ground.

-m