* Add public missing asyncio stubs for windows and proactor files, and any necessary private return/argument types.
* Add methods to BaseProactorEventLoop that mypy is complaining about, with note about status at runtime
* Add asyncio constants file
* Add types and functions in types.py that are new in 3.7
* Update `resolve_bases` to accept any iterable of objects, and the same
for `new_class` if the version is at least 3.7
* Add comparison overrides implemented by MethodWrapperType
* Fix mypy error due to over-constrained `__eq__`
