Add Entity support for box geometry

Still needs cleanup and tests.
Specs for BoxGraphics and BoxGeometryUpdater.
Merge branch 'geometry-updater-cleanup' into entity-box
Clean up.
Merge remote-tracking branch 'origin/master' into entity-box
Fix JSdoc type.
Add helper function for DataSource tests.

createDynamicProperty creates a ConstantProperty that reports itself as
dynamic, making generating test data easier.

Some other misc cleanup.
Better specs for dynamic box and ellipse geometry.
100% coverage for EllipsoidGeometryUpdater.
100% coverage for PolygonGeometryUpdater and RectangleGeometryUpdater.
100% spec coverage for WallGeometryUpdater
Merge branch 'entity-box' into entity-corridor

Conflicts:
	CHANGES.md
	Source/DataSources/DataSourceDisplay.js
	Source/DataSources/Entity.js
100% coverage for CorridorGeometryUpdater.