Mouse picking + more!

Can now cast a ray and return the first object hit.

I also wrapped most of the CustomKinematicController joint. This joint allows one to move an object directly, such as a moving platform, while still interacting with physical objects.

Combine these two and we have... Mouse picking! It is now possible to make objects so that they can be grabbed and dragged around with the mouse.

Next I will be adding the Player Controller, so that it is easy to make the player walk around in scene supporting stairs and slopes