add numba and geographic distance

[dgarnier]

I wanted to add a geographic distance, living near 40N, there is some reason for this. Secondly, I wanted it to go faster as I'm looking at hundreds of tracks which took 10s of minutes to get through. With numba, the loop spins through much faster.. probably still can be further optimized, but this is a big help and super easy. Tried to make it agnostic, but haven't tried it in a lot of places.