Implement `calculateBoundingBox()` method for `GeoJsonObject`s.

[zerobandwidth]

Add a calculateBoundingBox() method to GeoJsonObject, which would calculate (and reset) the object's bbox based on the instance's other attributes.

Class	Suggested Implementation
GeoJsonObject	Define it as abstract to force implementation classes to provide it.
Feature	Call this.getGeometry().calculateBoundingBox().
FeatureCollection	Get the box for each Feature in the collection, then draw a box around all results.
Geometry	Leave it abstract.
LineString	Might get away with using MultiPoint's implementation?
MultiLineString	Calculate min/max lat/long among all line endpoints.
MultiPoint	Calculate the min/max lat/long from all points.
MultiPolygon	Get the box for each Polygon, then draw a box around all of those boxes.
Point	Set a "box" at the point's coordinates.
Polygon	Calculate the min/max lat/long from all points on the outermost ring.

The order of the four double values must correspond to the order assumed in the definition of the bbox member of GeoJsonObject (whatever that is).

Consider calling this method automatically in any method that alters the shape of the object, such that the bounding box is updated in real time.