iD.geo.euclideanDistance should only be used for calculations of
projected coordinates or display (pixel) coordinates.
iD.geo.sphericalDistance calculates approximate geographical
distances, accounting for distortions at higher latitudes. This
can be used for determining the nearest node (operations.Delete,
actions.Circularize) or relative length comparisons (actions.Split).
It now calculates proper orthogonal projections and finds
the minimal one. Rename it iD.geo.chooseEdge and minimize
its coupling to context.
This version also copes with 0- and 1-node ways.
Fixes#1428.
