[ODE] dGeomSetOffsetPosition

[David Walters]

> If no-one objects I will put in the assert and new helper function.

I've submitted a patch for this new functionality. The new function
has been tested and behaves exactly as we had it the old way round -
but with one line of user code instead of 15. I like that :-)

Here it is:

http://sourceforge.net/tracker/index.php?func=detail&aid=1557801&group_id=24884&atid=382801

(I kept the function name as originally suggested :-)  ).

I think the only danger is that a user could potentially attach a mass
_before_ geoms and not get the same effect... I wonder if that is
something to be worried about? it seems a bit backwards to me.

Regards,
Dave