Moved the saveMarked queue over to the SetQueue system
- 4097 max capacity
-- Stores Cubes (SpoutRegion + SpoutChunk both extend Cube)
-- 4096 SpoutChunks + 1 SpoutRegion
--- Adding the region means save the entire region

- The save queue no longers uses TripleInts as the element

- The isValid() method in SetQueue checks if the chunk is loaded
-- ensures no unloaded queues are returned from the queue

- fixes a possible bug with generation where new chunks weren't saved
-- They were setModified, which triggers auto-save later