first draft of 'simple'
progress
... progress ...
removing a bit of 'silent'
... progress ...
right up to the edge ... nested sets are the next challenge
added test to show listenTo called on the same object
Add missing space in docs
Remove accidental global.
... progress ...
finished with the simple case for models ... hurrah
remove lingering silents
using 'current' instead of storing extra state
Use boolean for `nested`.
Pour one out on the ground for JSLitmus...
Merge pull request #1995 from braddunbar/simple

Use boolean for `nested`.
Only sort when a model is changed or added
Options everywhere
Speed up set, see http://jsperf.com/isobject-vs-typeof
Bring add optimization over to simple