Generics & typing module (support for module specializations)

[MikhailArkhipov]

• Instead of using protocols, provide proper implementation of IPythonModule that replaces standard module by specialized implementation.
• Ditto for any module member

Basically rework typeinfo wrapper

[zooba]

One of the other ideas of protocols was to be able to infer them from usage, so you could determine that a function parameter has a particular minimum type. This is much closer to how Python's type system actually works (annotations are an orthogonal type system that is different), and could provide value for our users distinct from what other tools offer.

[MikhailArkhipov]

#465