dBodyGetPreviousForce and Torque #15

It would sometimes be great (read: absolutely necessary) to be able to access the forces and torques accumulated during the last step, including all contact-forces and gravity.

dBodyGetForce only gives the accumulated forces of various dBodySetForce in preparation to the next step.

But if you want to do various control, sometimes it is vital to also know all accumulated forces of the previous step.

(submitted anonymously)

[Issue created by danielko: 2014-02-04]