Make Interpreter.Object, .Function, etc. into inner classes
Make Interpreter.Object, .Function, etc. into inner classes

Now methods on them (at least: ones defined in
Interpreter.installTypes) have access to the enclosing interpreter
instance.

Passes tests but type annotations are all broken.

google/CodeCity,NeilFraser/CodeCity,google/CodeCity,google/CodeCity,NeilFraser/CodeCity,google/CodeCity,NeilFraser/CodeCity,NeilFraser/CodeCity