Subpixel (Part I - Changes to the underlying API) (#364)

* initial cleanup on subpixel

* Homogenize subpixel API

* Updates API on the edge

* Updates for bug in > with tuples

* Updates subpixel API

* Adds tests and remove non-iterative iterative

* reverts edge changes

* Updates to add subpixel via NB and cluster

* Updates docs strings/tests/comments

* Fixes subpixel

* Fixes subpixel for rejecting template pts