count-index.go
func (countIndex *CountIndex) Add(point Point) {
	countIndex.Remove(point.Id())
	countIndex.currentPosition[point.Id()] = point
	countIndex.index.AddEntryAt(point).(counter).Add(point)
}
func (countIndex *CountIndex) Add(point Point) {
	countIndex.Remove(point.Id())
	countIndex.currentPosition[point.Id()] = point
	countIndex.index.AddEntryAt(point).(counter).Add(point)
}
// Add adds a point.