Mercator: Clamp latitude to valid range #103
Description
yFromLat() should clamp latitudes that all outside the valid Mercator range (+/- 85 latitude).
Clarify: What should happen to invalid latitudes (beyond +/-90)? Clamp them or throw exception?
Should also introduce yFromLatUnclamped() for performance reasons for callers that guarantee that latitudes fall within the Mercator range.
Related to #86, clarisma/gol-tool#112