Get rid of relative imports in all unittests. Now anything that

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. :)

Lib/test/test_mpz.py

@@ -1,6 +1,6 @@
 
 import mpz
-from test_support import vereq, TestFailed
+from test.test_support import vereq, TestFailed
 
 def check_conversion(num):
     mpz_num = mpz.mpz(num)