1D:
[ ] work on arithmetics ops
[x] manage overflow in (+)
[ ] manage wrapping in (-)
[ ] work on precision / scale ops
[ ] Declination ? 
[ ] Elevation ?
[ ] str::format! DD.DD DDMM.SS, similar to chrono::format!
3D: 
[ ] work on arithmetics ops
[ ] DMS3d::WGS84 conversion methods