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_threaded_import.py

@@ -6,7 +6,7 @@
 # randrange, and then Python hangs.
 
 import thread
-from test_support import verbose, TestSkipped
+from test.test_support import verbose, TestSkipped
 
 critical_section = thread.allocate_lock()
 done = thread.allocate_lock()