Remove Toolz reimplementations

[Kodiologist]

No description provided.

[allison-casey]

if by2s is going to be imported into other modules, it should have a docstring imo. Otherwise looks good to me

[Kodiologist]

Okay, I figured it didn't need one because it's only for internal use, but it's no trouble. Done.

[allison-casey]

doing the full autodoc args returns etc would be overkill, but it's good practice to have something for those methods.

didn't update docs conf.py to remove partition

[Kodiologist]

Oops, you're right. I forgot to check the whole docs directory. This PR was a surprising amount of work.

[allison-casey]

I can go through and fix the docs for you. by2s won't work since it doesn't support fillvalue and will drop the last entry if there's an odd number, but we can just use the itertools.grouper recipe for that

[Kodiologist]

That would be convenient. Thanks.

[allison-casey]

Docs are fixed for this and the itertools alias removals