Fix protocol typing

[yelite]

And remove most "type: none". Fixes #138

Previously I forgot to add Protocol as base class to the ModelModule. That makes ModelModule non-protocol, breaking lots of typing.

Note that inheriting from an existing protocol does not automatically turn the subclass into a protocol – it just creates a regular (non-protocol) class or ABC that implements the given protocol (or protocols). The Protocol base class must always be explicitly present if you are defining a protocol

https://mypy.readthedocs.io/en/stable/protocols.html#defining-subprotocols-and-subclassing-protocols

cc @masahi @sunggg

[masahi]

cc @jroesch