mark-p-thomas : GeoJSON Collections

GeoJSON collections are GeoJSON objects that serve merely to be collections of other GeoJSON objects of a constrained type. They are implemented using a Delegation Pattern.

The GeoCollection abstract class is the base class for delegate classes included within the FeatureCollection & GeometryCollection classes. The abstract class performs the generic & basic functions of handling a collection of immutable GeoJSON objects, while the derived delegate classes serve as defining the type constraints of the objects allowed.