Faster __contains__ impl for SortedListWithKey
Make SortedListWithKey faster for value_orderable=False, improve testing, and add stress
Merge branch 'slwk_faster'
Merge branch 'master' of github.com:grantjenks/sorted_containers
Prevent infinite repr recursion and allow easier subclassing; also improve repr tests
Bump version to 0.8.4. Faster SortedListWithKey and better __repr__ with comprehensive testing.