Renames functional extension module to _functools and adds a Python
functools module so that utility functions like update_wrapper can be
added easily.

some useful features of regular functions:

* Made weak referencable.
* Allow attribute access so a user can set __name__, __doc__, etc.

Combined efforts of many including Peter Harris, Hye-Shik Chang,
Martin v. Löwis, Nick Coghlan, Paul Moore, and Raymond Hettinger.