#69: Allow restcfg.json to work against Layer Definitions. Add a new example to demonstrate and verify this.
Bump REST API version
Add support for special computed properties when restcfg.json data source is a Layer Definition. Fixes #69

Add support for outputting extruded geometry based on pre-evaluated elevation properties when restcfg.json data source is a Layer Definition.

Also constant-ify some string constants.