[Python-porting] Pickling unbound methods on Python 3

["Martin v. Löwis"]

> I can think of a few solutions:
>
> 1. Make `save_global` look in the classes inside the module as well.

How exactly would you do this? I don't think this is implementable,
in a reasonable way.

> 2. Allow me to specify a reducer for FunctionType.

How would the reducer work?

Regards,
Martin