Modifies code to focus on large area tiling with small texture maps that are stitched together to make one large bitmap.
More configurable tile density with corrected target centring.
tweaks to make globals that control grid easier to configure.
Tunes location and range to be middle of KSEA data in 10.25 with some margin.
Crude but working progressive data sampling of needed tiles. 5 tiles sampled per frame.
Massive refactoring into GUI window tool.

Last commit of semi working code before we really get stuck in and hack this into something cleaner.