Use the python3 names in docstrings

[asottile]

collections.X => collections.abc.X so links in docs work better

[dahlia]

I believe it's better to use Python 3 type names in docs, and although we don't use typing, generic types it provides are quite useful for docs at least. For example, typing.Set[str] shows details while no collections.Set nor frozenset do. With Sphinx ReST, it can be written as like:

(:class:`~typing.AbstractSet`\ [:class:`str`]) The set of keywords :func:`compile()` can take.

The downside is a such markup is not very clean when it's compared to the way we've written previously. What's your opinion?

[asottile]

ooh yeah the typing names would be better. I'll try that in a followup and see how it looks. Bummer about the sphinx syntax though :/