make class skipping decorators the same as skipping every test of the class

This removes ClassTestSuite and a good bit of hacks.
diff --git a/Misc/NEWS b/Misc/NEWS
index 89160ff..5526d9c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -302,6 +302,9 @@
 Library
 -------
 
+- In unittest, using a skipping decorator on a class is now equivalent to
+  skipping every test on the class.  The ClassTestSuite class has been removed.
+
 - Issue #6050: Don't fail extracting a directory from a zipfile if
   the directory already exists.