[ODE] ODE in its own thread

[Patrik Stellmann]

Since I have several threads - one per view to render and several others 
to simulate sensors and controllers - that need to access imformation 
about the objects I'm running ode in another thread (synchronization is 
done via a request queue and at every time only one thread is running 
while the others wait). But I didn't do that to get any performance 
boost but simply because any single threaded way would be way more 
complex...