New tile queue implementation (heapify-powered)
Sort object properties
Set frame state immediately after rendering
Fix key usage
Discard unwanted tiles from tile queue
Rename tileUsage to usedTiles
Only update wanted tiles if not all tiles are loaded
Use Infinity rather than undefined to drop tiles
Optimize tile dropping in reprioritize
Remove stale FIXME
Clear queued tile keys when queue is cleared
Use stricter types in private methods, operate on array directly
Ensure dropped tiles are properly removed from tile queue
Remove unused TileQueue clear method
Remove unused Jasmine matchers
Merge pull request #126 from openlayers/tilequeue

Tile queue requires optimizing