Prototypes with typeclasses

This branch has a few additional random optimisations than specifically prototypes for datatypes and typeclasses, but here it is anyway.

- Prototypes for data types
- Prototypes for typeclasses
- No empty `__superclasses` anymore
- Typeclass objects now have the superclasses as direct properties rather than stored inside a `__superclasses` object
- Applications like `f({})` to force thunks are now inlined to just be regular javascript `f()` calls.
I'm not sure. I think I'd rather define something like `foreign import undefined "var $$undefined = undefined;" :: Prim.Undefined` in Prelude if that's possible