void SpatialTransform::setOrientation(const Orient& orient)
{
  setConfiguration( Transform(getPosition(), orient) );
}
base::Transform SpatialTransform::getConfiguration() const
{
  if (child)
    return child->getConfiguration()*tinv;
  return Transform();
}
void SpatialTransform::setPosition(const Point3& pos)
{
  setConfiguration( Transform(pos, getOrientation()) );
}