1. Update CHANGES and reference documentation.
2. Add support for KML Feature `visibility` element.
3. Make dynamic updates obey Entity.isShowing.
4. Make static material and outline geometry obey Entity.isShowing.
5. Update specs.
6. Add Sandcastle example
7. To support the Sandcastle example, chaned `viewer.zoomTo` and `viewer.flyTo` to be "best effort" functions, rather than failing if any one entity is not displayed. This was both requested on the mailing list and is needed to zoom to a data source on load or with time-dynamic data.
Matthew Amato