Highlight save button when save is needed
Disabel save button when no save is needed
Only add save watch if we really need it
Restore saver.needsSave upon successful save.
Call correct success function for 406 saves
Remove $timeout from saver (was used to debug)
Extract StateChange factory
Experimental usage of StateChange in state

Only for head changes right now.
Fire change event on state.change
Listen to change event in saver to activate saving
Mark changed sentences/chunks in navigator
Only update sentences with changes in persister
Refactor TreebankPersister and update spec
Execute state.change properly
Add state.lazyChange, later used for batch changes
Add optional preExecFn in StateChange
Add deprecation warning to state.setState
Use state.change in morph
Add a human-readable message to StateChange
Refactor StateChange (more private functions)