Further refactored in preparation for SpeedOverGroundAnalysis. And added more unit test coverage. (AISAB-52).
Added SpeedOverGroundAnalysis and SpeedOverGrounEvent. Also various minor code changes to make user experience make sense with more event types (AISAB-52).
Do not perform CourseOverGroundAnalysis for tracks with sog < 2 (AISAB-51).
Bug fix for SpeedOverGroundAnalysis (AISAB-52).