cache, I was only checking currently visible tiles, rather than checking all the cache entries.
scene graph when a tile shift occured while the tile load queue was not empty.
Better handling of missing tiles. Added a range selector so we can completely ignore tiles that are beyond our visibility range. Added a routine to prep the ssg nodes before rendering by updating the transform and range selector values.
SimGear and TerraGear appear to have been split off at this time.
