OARIS11 — Name "wgs84_velocity_type" is misleading

The name suggests something like degrees latitude per second, degrees longitude per second; probably a usable unit but not one I have ever come across. It was certainly not where I looked when looking for course and speed. I did look at polar_velocity_type, found it was wrong and used cartesian intead, which was not what my subscriber was expecting.

Admittedly it is obvious once one finally drills down to the definiton of wgs84_velocity_type, but experience shows that at least this developer did not search that far.

Add further explanation to velocity_coordinate_type

Explain the nature and purpose of the 3 velocity variants. Add explanation to wgs84_velocity_type that reports velocity from the viewpoint of the object in terms of course and speed with optional angle of climb for changes in height.