I like the idea of the Transformation object, but I think the API is backward. It should be that you call a function, like `find_translation_and_rotation`, and it returns the transformation, not the other way round. A relatively nice API to look at is the transform API in `skimage` for image processing. http://scikit-image.org/docs/0.7.0/api/skimage.transform.html#skimage.transform.estimate_transform.

We should have interfaces for the following operations given `src` and `dest:
- align `src` to `dest`, modifying `src` inplace.
- align `src` to `dest`, returning the rotated/translated version of `src`.
- align `src` to `dest`, returning the rotation/translation operator object, but not modifying either conformation.