Add WorldWind as a Layer Preview format

[emxsys]

In the GeoServer | Layer Preview web interface, add WorldWind as preview option. The WorldWind preview would display the selected layer on a WorldWind globe in the browser, similar to the way GeoServer displays OpenLayers.

• The WorldWind preview option would need to be configured with a base map layer and elevations
• Add WorldWind as an available format for WMS raster layers
• Consider adding WorldWind as a WFS format for rendering feature data with KML
• Add a new GeoServer mime type, e.g., "format=application/worldwind"
• Consider configuration settings for external layer/elevation dependencies

[emxsys]

This feature should be added to the WorldWind Core UI module.

[emxsys]

This feature was superseded by the WWSK Explorer implemented in issue #107. With the Explorer, the ability to look at a single layer is available plus many other features. Thus this feature is redundant.