Renamed SwitchableMapView to CyclingMapView.
Add SwitchableMapViewContainer.
Remove GLContextHolder and replace it with GLContextManager.
Refactoring and cleanup of map view code.
Add three pane split map view.
Rename SplitterWindow to SplitterWindow2.
Added SplitterWindow4.
Added four pane map view.
Implement more map views and cleanup.
Add preference setting for map view layout.
Refactor notifiers to allow observers to be removed and added during notification.
Skip stale observers during notification.
Some changes in notification code and toolboxes.