We want to run the fit on the non-centered points to yield the center
of the ellipse in the returned array.

This class mainly manages a collection of epicells, has
static methods for its creation from images, and has some
methods for plotting things.

The transform back is not correct yet.
See how to make the fit and rotation with respect to point centers,
then translate ellipse back at the right coordinates.

Subfunction that does only fit on 2d points (no matrix rotation).
Fixed the quadratic to cartesian conversion.

and back.

Like S. Herbert did.