Change SortedDict to inherit from dict directly: 29% faster getitem, 29% faster contains, 12% slower setitem_existing
Add key parameter to SortedDict (no tests yet)
Put key before load param
Remove value_orderable from SortedListWithKey
Change lambda to identity module function
Put key before load in constructor call
Add SortedListWithKey to SortedList performance comparison
Remove Pair.__getitem__
Add blist.sortedlist(key=identity) to SortedList performance comparison