OARIS11 — Option for an explicit bearing only track origin

Particularly when reporting bearings from an off-board or otherwise mobile sensor it would be more convenient, natural and precise to report the bearing origin as part of the report rather than referring implicitly to some otherwise well-known origin as the spec currently states (e.g. by reference to another track).

Add Support for Explicit Origin Reference for Bearings

Extend coordinate_origin_type to include an Explicitly Specified enumeration. Add an optional WGS84 origin attribute to polar_position_type and polar_position_accuracy_type. It is only useful to explicitly specify the origin in an absolute coordinate system, if in a relative system the ultimate question of coordinate origin is still unresolved and must rely on implicit information.