Implement dJointGetHinge2Angle2

[Daniel K. O.]

The Hinge2 joint doesn't have a way to measure the angle for the second hinge.

There's a partial implementation from the old tracker: http://sourceforge.net/p/opende/bugs/90/ by Luc.

A similar implementation is on KODE: http://bitbucket.org/danielko/kode/src/default/src/joints/Hinge2.cpp?at=default

It consists of calculating reference vectors for the second body (like v1 and v2 are there for the first body).

[Daniel K. O.]

resolved issue #12 : added dJointGetHinge2Angle2

→ <<cset b3ac898a53cf>>