Document the output units of the distance function

[hmwesigwa]

What are the outpu units for the function distance(a, b, [datum = wgs84])?
Is there a function included to convert that distance to miles?

[andyferris]

Everything is currently implement in SI units, so you get metres.

Do you think using a seperate package for unit conversion would be suitable?

[andyferris]

Recall also that distance is direct Cartesian distance so far - we'd love to support geodesic distances too.

[hmwesigwa]

Great thanks! A package for unit conversion would definitely be convenient. Also mentioning that everything is implemented in SI units in the readme file would also be helpful to others. Thanks for the great work!

[andyferris]

Here's 4 unit packages that I'm aware of:

• https://github.com/ajkeller34/Unitful.jl
• https://github.com/dhoegh/EngUnits.jl
• https://github.com/Keno/SIUnits.jl
• https://github.com/timholy/Units.jl

Not sure what is best for a simple conversion (most of these aim to assert correct dimensional analysis)