Support geodesic drawing (i.e globes)

[JamesLMilner]

At the moment drawing on a globe seems to be mostly supported having tested with MapboxGL JS globe projection.

The one thing that seems to be broken is midpoints as they appear slightly off. It may be that we simply need to implement a rhumb line midpoint which can be toggled with a parameter to polygon mode.

There may be other things that don't function quite as expected on globes so I'll keep this issue open as a catch all for now.