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. :)

    Wasn't built on Windows; not in config.c either.
    Module init function missing DL_EXPORT magic.
    test_xreadline output file obviously wrong (started w/ "test_xrl").
    test program very unclear about what was expected.