[ODE] Patch for new function dBodyGetWorld submitted

[Christoph Beyer]

this patch is for an new very useful function for the API:
ODE_API dWorldID dBodyGetWorld (dBodyID);

this function retrieves the dWolrdID of a Body who is attached to a 
world (or zero if not attached).
I'm using this function in my program and it works fine!

cheers

Christoph