Clean up hash.coffee
Make hashes fire change events if the key already exists.
Tests for new hash events.
WIP better view API
Add data-batman-view property to nodes owned by a view. For debugging.
Make data-view a special case of a yield.
Remove render contexts and bind everything to the view lookup chain.
All hash events include the added or removed values in the callback.
Use new hash event syntax for view subviews.
ViewBindings use subview constructor name for better debugging.
Add $context for easy view lookups.
Fix data-view-* options.
Make data-context and data-context-* work again.

Problems:
- Doesn't pop the context after exiting the node
- Chain lookup needs to happen before view lookup
- Named contexts also need to happen during chain lookup
Fixes for hash.clear using the new hash events
Implemented IteratorBinding using new view API
Smarter collection change events for IteratorBinding
Remove 'data-mixin'
Fix ensure iteration item has a unique ID
Fix hash tests
Pass arrays instead of splats to SimpleSet change events.