WMTS object model alignment

[zglueck]

Child of #551

The WebWorldWind WMTS implementation should be aligned with the WorldWindAndroid implementation. While most of the architecture and property naming does match between the two SDKs, the following items have not been resolved:

• [ ] WmtsLayerCapabilities -> WmtsLayer rename (pending current WmtsLayer future)
• [ ] plural property names (e.g. layer vs layers) in array based properties
• [ ] boundingBox assumes two values in the upper and lower corner elements (Android just stores the strings) The specification indicates only two values

Completing these items may introduce breaking changes or name space conflicts into the current implementation, based on commit 9bd0d5d.

[pdavidc]

@zglueck Is there still merit in aligning the WMTS interfaces between Android and Web today?

[zglueck]

@pdavidc the property names not matching plurality case is minor (checkbox 2). The structure between WWW and WWA should be fairly consistent as well.

As you know, the layer names and mechanism for creating a layer are much different. I don't see much merit in converting to the WWA approach, unless WWW WMS was changed and a LayerFactory (or something analogous) were added.

Bottom line, I don't see any further work for alignment unless we want to emulate a WWA factory approach with generic TiledImageLayer.

[pdavidc]

@zglueck Let's ensure that Web WMTS classes and property names match the names used in the OGC spec (with the exception of WmtsLayerCapabilities), then close this issue.