Spigot patch: 0014 Alternate, sync-free-but-safe chunk reference cache

https://github.com/EcoCityCraft/Spigot/blob/d9c76252eb02f7d0d6bea11efe77e3bb1edb0d99/CraftBukkit-Patches/0014-Alternate-sync-free-but-safe-chunk-reference-cache.patch