- addTrackEntry() needs to scroll the entry in view
- added HistoryView
- added RightPaneFoler and moved HistoryView into it
- major refactor of models, controllers
- all models use IModelComponent and have their state created
  and pushed into them by ApplicationStates
- refactored CommandController delegation to ApplicationController
- added IApplicationController, all commands registered here
- implemented TrackEntryNodeMoveCommand
- arranger numMeasures is in MachineModelState now
- MachineModel; selected channel, mouse down on track channel selects
- highlight the mixer section of the selected track
- TrackPane hit test  changes selectedChannel in MachineModel