MMKClosestPoint
| extern MMKPoint *MMKClosestPoint(MMKPoint *point, MMKSegment *segment) | 
Find the point on a given segment (great-circle arc or shorter arc) that is closest to a given point.
| extern MMKPoint *MMKClosestPoint(MMKPoint *point, MMKSegment *segment) | 
Find the point on a given segment (great-circle arc or shorter arc) that is closest to a given point.