Behavior of piston

A user reported that behaves unexpectedly, i.e. pointing in the wrong direction after being initialized with a non-orthogonal direction and possibly after being reset or relocated.

The branch so far contains several attempts to reproduce the problem, without success.

Since no failure example was provided, it cannot be excluded that the problem lies in unexpected usage of the piston joint (admittedly, the correct usage is not always very intuitive, see ODE Wiki).