Adds support for using select.poll() if it's available

    Move a 'map is None' test out of an else branch and into the right place

was raised.  This occurred during installation.

    (SF patch 101447, fixing PR#113704)

*this* set of patches is Ka-Ping's final sweep:

The attached patches update the standard library so that all modules
have docstrings beginning with one-line summaries.

A new docstring was added to formatter.  The docstring for os.py
was updated to mention nt, os2, ce in addition to posix, dos, mac.

standard Python library.  (Async socket support.)