def add_point(lat:, lon:, elevation:, time:)
      time = Time.parse(time) if ! time.is_a?(Time)

      current = [lat, lon, elevation]

      if @start_time.nil? || time < @start_time
        @start_time     = time
        @start_location = current
      end

      if @end_time.nil?   || time > @end_time
        @end_time     = time
        @end_location = current
      end

      @points[time.to_i] = current

      true
    end
def add_point(lat:, lon:, elevation:, time:)
      time = Time.parse(time) if ! time.is_a?(Time)

      current = [lat, lon, elevation]

      if @start_time.nil? || time < @start_time
        @start_time     = time
        @start_location = current
      end

      if @end_time.nil?   || time > @end_time
        @end_time     = time
        @end_location = current
      end

      @points[time.to_i] = current

      true
    end
add a point to the track

 @param [Float] lat latitude
 @param [Float] lon longitude
 @param [Float] elevation elevation
 @param [Time] time time at the given location