WIP: Add an orthogonally indexable attribute to ndarray - #5749

This looks really nice @jaimefrio! I did not realize doing orthogonal indexing without converting slices into ndarrays was possible.

For putting together a test suite, these tests I wrote for xray might be helpful:
https://github.com/xray/xray/blob/v0.4.1/xray/test/test_indexing.py#L28

Oh wow, I forgot about this one, so you actually had figured out all the reordering in python code, pretty nice (tends to be a bit mind boggling, eh ;))! Actually this could be useful for testing in principle, though probably better to just write extensive example tests.

To link it though, I think gh-6075 probably supercedes this.

Closing this in favour of my stuff for now (if you hate me for it, just reopen and tell me :)), though it is actually very nice, and maybe we should at least keep it in mind. Because of that, I will mention that I think the code does not handle boolean arrays as is ;).