fromlist to get __import__ to return the module desired. Now it uses the proper
approach of fetching the module from sys.modules.

Closes issue #9252. Thanks to Alexander Belopolsky for the bug report.

recv() and send()

non-blocking mode: they return None when an operation would block (instead
of raising an exception).

(GNU/Hurd is not dead)

So failed to load tcl/tk dll because $(dist)/tcltk/bin was set to PATH as
relative path. (Windows)

Previous commit changed macpath but macpath is not used anymore as os.path

directly. It used to be built with bzip2's makefile.

Store all errors signaling a disconnection into a global frozenset to save some computation time on recv() and send().