Change coords name

Coords name have been changed from lon/lat to longitude/latitude for consistency.

Signed-off-by: Emanuele <feliziani.emanuele@gmail.com>
Add Haversine calculation helper method

Add a helper method for calculating distances with the Haversine formula. Sweetness galore.

Signed-off-by: Emanuele <feliziani.emanuele@gmail.com>
Test the thing

Test to check distance calculation.

Signed-off-by: Emanuele <feliziani.emanuele@gmail.com>