Converted to use "segments" for performance reasons. Will need to get this working fully on iPad and do more experiments to see if this is worth it.
I've created a new Grid class that will hopefully improve overall performance. Added it to the project but have not integrated into the code yet.
Grid is integrated. Still needs more testing, debugging, and refactoring.
Fixed some major scrolling bugs caused by the grid.
Modified intersection code to no longer use object literals (for GC performance)