Test use of projections

[sgoodm]

Using appropriate projections could provide a more accurate distance calculation but may have a significant performance cost.

I'd like to test:

• how much distance calculations actually change (in various scenarios)
• performance differences

[mmann1123]

Assuming you could just check the if the CRS unit is degrees or not and switch between haversine and euclidean distance no?

[jacobwhall]

At the very least I think we should warn users if there is a potential inaccuracy, and it would be great to add support for euclidean distances.