Better exception messages for unittest assert methods.

- unittest.assertNotEqual() now uses the inequality operator (!=) instead
  of the equality operator.

- Default assertTrue and assertFalse messages are now useful.

- TestCase has a longMessage attribute. This defaults to False, but if set to True
  useful error messages are shown in addition to explicit messages passed to assert methods.

Issue #5663
diff --git a/Misc/NEWS b/Misc/NEWS
index 036a061..dd8c0ad 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -202,6 +202,14 @@
 Library
 -------
 
+- unittest.assertNotEqual() now uses the inequality operator (!=) instead 
+  of the equality operator.
+  
+- Issue #5663: better failure messages for unittest asserts. Default assertTrue
+  and assertFalse messages are now useful. TestCase has a longMessage attribute.
+  This defaults to False, but if set to True useful error messages are shown in
+  addition to explicit messages passed to assert methods.
+  
 - Issue #3110: Add additional protect around SEM_VALUE_MAX for multiprocessing
 
 - In Pdb, prevent the reassignment of __builtin__._ by sys.displayhook on