Improve geodesy calculations and test coverage.

[halmueller]

Background

The underlying formula in coordinateWithBearing(bearing:distanceMeters:) used incorrect logic for determining the radius of the earth at the given latitude, so that function returned slightly incorrect results. This PR addresses that error, and adds unit test coverage for that function and its supporting functions.

I believe that the implementations of translatedLocation(with:) and translation() are still not quite right. I've added the most basic test coverage possible, with an enormous accuracy bound, but these two functions need some analysis. I'll open a separate issue for that, but will move on for the time being, since they seem to work ok in the field.

Resolves issue #239 (the accuracy part, not the Google Maps suggestion).

Breaking Changes

Any use of coordinateWithBearing(bearing:distanceMeters:), or of translatedLocation(with:), will see slightly different results.

Meta

• Tied to Version Release(s):

PR Checklist

• CI runs clean?
• Appropriate label has been added to this PR (i.e., Bug, Enhancement, etc.).
• Documentation has been added to all open, and public scoped methods and properties.
• Changelog has been updated
• Tests have have been added to all new features. (not a requirement, but helpful)
• Image/GIFs have been added for all UI related changed.

[Pilot-Marc]

Accuracy is immensely improved. I like the idea of a second pair of eyes on this, but I approve.