addset: promote to real smartset
Better revset performance are also achieved with less overlay. There is no good
reason for addset to not be a smartset. We can replace the `_orderedsetmixin`
inheritance since `abstractsmartset` has efficient min and max too.
--- a/mercurial/revset.py Fri Oct 03 00:12:22 2014 -0500
+++ b/mercurial/revset.py Thu Oct 02 19:42:06 2014 -0500
@@ -2554,7 +2554,7 @@
self._subset.reverse()
self._ascending = not self._ascending
-class _addset(_orderedsetmixin):
+class _addset(abstractsmartset):
"""Represent the addition of two sets
Wrapper structure for lazily adding two structures without losing much