Module legacy

Select appropriate function to call as a replacement
for class.__setstate__ at runtime.

selector must return None if the class_'s original method is
to be used; otherwise, it should return a function that takes
an instance of the class and the state.

pre_super and post_super determine if super(class_)'s
__setstate__ should be invoked before or after (respectively)
calling the function returned by selector. If selector returns
None, super(class_)'s __setstate__ is never called.

Install a class named 'old_name' in 'module'; when created, the class actually returns an instance of 'new_class'.

new_class_args allow any arguments to be supplied to new_class before other arguments are passed at creation time.