*WIP* chest API
fix crash when player causes entityGone message
chests kinda working.

Problems to fix before merging:

 * withdraw breaks for more than 1 item
 * deposit breaks for more than 1 item
 * if you open a chest, close it, and open it again, the bot crashes
   with no error message.
 * when the chest has a negative x coordinate, it can't open
 * rename item.meta to item.metadata