Class proxy should be more lazy

We currently perform a full scan of the method table when you first access a class to ensure that the dir() function works. That slows down initialization, and uses more memory than needed.

What's worse is that we basicly do a rescan on every method calls, and that is way to expensive (the rescan is needed because the runtime doesn't have a callback API for changes).

All of this can be done lazily with Python 2.6 or later:

Implement dir, perform a full scan there to ensure that

introspection works

Do not perform a full scan when loading the class, or when calling

a method

In getattribute: cache that a method was found, probably even

when the method is found in a superclass (to avoid slowdown when calling methods defined in a superclass)

This means we can no longer add special methods by looking

for selectors after doing the full scan (e.g. add getitem when Aleksey Marchak(valueForKey:) is defined), switch to explicitly adding special methods to particular classes instead.

Issue #12 was marked as a duplicate of this issue.

I have a (local) 3.0 branch where I've implemented this. The code still needs some cleanup, but basicly works.

This is implemented in the 3.0 branch.