Not backported because of behaviour change.

imports e.g. test_support must do so using an absolute package name
such as "import test.test_support" or "from test import test_support".

This also updates the README in Lib/test, and gets rid of the
duplicate data dirctory in Lib/test/data (replaced by
Lib/email/test/data).

Now Tim and Jack can have at it. :)

allows using the tests with unittest.py as a script.  The tests will
still run when run as a script themselves.

+ test_quopri.py relied on significant trailing spaces.  Fixed.
+ test_dircache.py (still) doesn't work on Windows (directory mtime on
  Windows doesn't work like it does on Unix).

Modified by Fred Drake.
This closes SF patch #440827.