Make ol.source.TileImage#tileCache protected, not private
Make ol.source.TileImage#crossOrigin protected, not private
Make ol.source.TileImage#tileLoadFunction protected, not private
Refactor ol.source.Zoomify to use a private tile class
Remove unused variable
Tidy up ol.source.Zoomify tile grid calculations
Tidy up ol.source.Zoomify tile URL calculations
Use prettier image in zoomify example