Add StandardError to the kill list for Python 3.

pep-3100.txt

@@ -190,6 +190,8 @@ To be removed:
 * ``intern()``: put in ``sys`` [2]_, [22]_ [done]
 * ``reduce()``: write a loop instead [2]_, [9]_ [done]
 * ``xrange()``: use ``range()`` instead [1]_ [See range() above] [done]
+* ``StandardError``: this is a relic from the original exception hierachy; subclass
+  ``Exception`` instead.
 
 
 Standard library