[ODE] Geom offset support

[Geoff Carlton]

I've finally added geom offset support to UNSTABLE.

The following functions have been added:
  void dGeomSetOffsetPosition (dGeomID, dReal x, dReal y, dReal z);
  void dGeomSetOffsetRotation (dGeomID, const dMatrix3 R);
  void dGeomSetOffsetQuaternion (dGeomID, const dQuaternion);
  void dGeomSetOffsetWorldPosition (dGeomID, dReal x, dReal y, dReal z);
  void dGeomSetOffsetWorldRotation (dGeomID, const dMatrix3 R);
  void dGeomSetOffsetWorldQuaternion (dGeomID, const dQuaternion);
  void dGeomClearOffset(dGeomID);
  int dGeomIsOffset(dGeomID);
  const dReal * dGeomGetOffsetPosition (dGeomID);
  const dReal * dGeomGetOffsetRotation (dGeomID);
  void dGeomGetOffsetQuaternion (dGeomID, dQuaternion result);

All existing code should be unaffected, and the old geomTransform can 
still be used alongside this new method.  I've tested the code with some 
unit tests, which have also been added.  I ported them from cxxtest over 
to cpptestharness, which I found somewhat less convenient, but they 
should be there and running.

Sound out if there are any teething problems with these changes.

Cheers,
Geoff