Combine the functionality of test_support.run_unittest()
and test_support.run_classtests() into run_unittest()
and use it wherever possible.

Also don't use "from test.test_support import ...", but
"from test import test_support" in a few spots.

From SF patch #662807.
diff --git a/Lib/test/test_userstring.py b/Lib/test/test_userstring.py
index a821456..990199e 100755
--- a/Lib/test/test_userstring.py
+++ b/Lib/test/test_userstring.py
@@ -44,9 +44,7 @@
         getattr(object, methodname)(*args)
 
 def test_main():
-    suite = unittest.TestSuite()
-    suite.addTest(unittest.makeSuite(UserStringTest))
-    test_support.run_suite(suite)
+    test_support.run_unittest(UserStringTest)
 
 if __name__ == "__main__":
     test_main()