Adding __array_function__ support to random operations (like shuffle)

[jakirkham]

It would be really useful when operating with other array libraries to support __array_function__ on numpy.random functions (like shuffle) so as to dispatch to other implementations for those arrays.

[jakirkham]

Any thoughts on whether this would be ok to do?

[rgommers]

It looks to me like there are three functions for which this would make sense: shuffle, choice and permutation. Those operate on an existing array rather than generating a new one from some input parameters.

+0.5 from me

[mikeiovine]

Hi all,
I noticed that this issue is quite old, but I was messing around recently and wanted to provide a custom implementation of shuffle for my ndarray subclass. I made some simple changes and opened a PR. Hope this is OK, suggestions welcome :)