Improve wrapping

[Helveg]

Currently whether an object should be wrapped is determined every function call:

    def __getattr__(self, attr_name):
        # Get the missing attribute from h, if it requires wrapping return a wrapped
        # object instead.
        attr = getattr(self.__h, attr_name)
        if attr_name in self.__requires_wrapping:
            return self.wrap(attr, attr_name)
        else:
            return attr

This can be improved by overriden the PythonHocInterpreter at the end of its instantiation for all things that should be wrapped and don't override the function already.

[Helveg]

To allow subclasses of the PythonHocObject classes to be created both before and after the PythonHocInterpreter class has been created and still wrap all of them I think this approach is best:

• In __init_subclass__ add the new hoc object class to a list on the interpreter.
• In the interpreter class store a weakrefs to every interpreter.
• Create wrappers when interpreter is created.
• Add wrappers to every interpreter when a class is created.