Remove quad_tile library and extract to gem Quad tile functions are now installed via a gem with native extension automatically. This improves the run time of the test suite by ~30% for users that didn't bother to build the C version of the functions. Closes #1314 Closes #1899
Fix C version of QuadTile#tiles_for_area to return correct tiles
Refactor bounding box code Moved duplicated code into the BoundingBox class, and pass around BoundingBox objects instead of lists of bounds.
Add a C implementation of QuadTile.iterate_tiles_for_area
QuadTile infrastructure.