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.

based on a suggestion from Tim Peters; also make sure that we're really
doing exponentiation and not multiplication.

are auto-coerced to longs now, but this test still expected OverflowError.
I can't imagine this test failure was unique to Windows.