This update adds cache to aren to protect it during server failure.

Example: During the game blocks in the arena disappear and the server consumes all resources and is overloaded, starts to shut down and saves our arena when there are no blocks loaded. The file with the arena name will be saved in the Cache folder and the block locations in the arena will be stored there. After re-starting the game in a given arena, the blocks from the file are loaded and our arena is thus renewed.