points-index.go
func (points *PointsIndex) Add(point Point) {
	points.Remove(point.Id())
	newSet := points.index.AddEntryAt(point).(set)
	newSet.Add(point.Id(), point)
	points.currentPosition[point.Id()] = point
}
func (points *PointsIndex) Add(point Point) {
	points.Remove(point.Id())
	newSet := points.index.AddEntryAt(point).(set)
	newSet.Add(point.Id(), point)
	points.currentPosition[point.Id()] = point
}
// Add adds a point to the index. If a point with the same Id already exists it gets replaced.