Multiple bug-fixes for PU the joint.
(1) Joint no longer assumes that Body 1 is anchored at its PoR.
(2) No longer assumes that the first universal axis is orthogonal to the prismatic axis.
(3) The prismatic axis motor correctly applies torque to the bodies as a result of forces not going through the center of mass.
(4) The prismatic axis is now set correctly with Reversed joints.
See forum discussion: https://groups.google.com/d/topic/ode-users/Ym86EU--um0/discussion