def endpoint(distance, azimuth)
      phi2, la2 = @globe.direct(phi, la, distance, deg2rad(azimuth))
      Coord.from_rad(phi2, la2)
    end
def endpoint(distance, azimuth)
      phi2, la2 = @globe.direct(phi, la, distance, deg2rad(azimuth))
      Coord.from_rad(phi2, la2)
    end
Given distance in meters and azimuth in degrees, calculates other
 point on globe being on that direction/azimuth from current.
 Vincenty formula is used.

    kharkiv = Geo::Coord.new(50.004444, 36.231389)
    kharkiv.endpoint(410_211, 280)
    # => #<Geo::Coord 50°30'22"N 30°31'53"E>