Remove --fast-parser option

The parser for mypy was changed permanently. The 'fast' parser is no
longer opt-in-able. (Rather, it became possible to opt-out of it.)

Use correct flags

--fast-parser for async/await support
--ignore-missing-imports --follow-imports=skip for not following imports and causing odd errors

Update README.md

Update README

Fix bug in autoload code

Setup

Initial commit