[ODE] correctly using dContactGeom structur

[Christoph Beyer]

Well, i will ignore 'side1' and 'side2'.

there is still one question open:

the penetration is always a volume, so is 'pos' the middle of the penetration
    something else?

i tested it and it works well in all penetration-pos methods,
i think it is not very important for accuracy,
but if i know the intended use, i can improve the accuracy
a little bit. 


thanks

chris