Fix Ellipse module

[byorgey]

The change back to a linear map + translation representation of affine transformations (from a projective representation) means that the Ellipse module is now broken, since it depended on the internals of how transformations were being represented. However, I think this also represents an opportunity to considerably shorten the Ellipse code since it seems that part of what it was doing before was manually computing the transpose matrix of the transformation, whereas now the transpose of transformations is available directly.