This includes updating the ignore comments for things which mypy
now knows about or now complains about, as well as pulling in some
typeshed packages for things outside the standard library.
No fixes yet, this just gets the config in place.
Note: I'm assuming that we'll pick up a change to parso such that
it exposes its type stubs here. Otherwise we'll want to tweak the
imports config to ignore those errors.
In particular this improves support for detecting usage of various
type annotation usages and adds support for correctly parsing
type: ignore comments which contain a reason tag.
This tells wheel that the packages are compatible with Python 2 and 3.
The wheel currently on PyPI is only tagged 'py2', so installing on
Python 3 uses the sdist.
