Blender Git Loki

early out for ortho grid drawing

Helps most when real-world units are used.

Previous code started at the smallest visible unit (e.g. Inches) then
followed to Feet, Yards, Chains, Furlongs, Miles. Always to the largest
unit of the set, even though most would be way off screen.

New code knows whether it skipped any grid lines for the next unit to
fill in, can stop once all lines are on screen.