Fixed backpacks to work properly
Contents are saved in SQL database. Inefficently, but temporary.
When a more efficient method is made, will update code and include function to upgrade database contents
Commands:
	/backpack
		Opens your own backpack
	/backpack <player>
		Opens players backpack
	/clearbackpack
		Clears own backpack
	/clearbackpack <player>
		Clears players backpack
Permissions:
	backpacks.self
		Allows player to open their own backpack
	backpacks.other
		Allows to open other players backpacks
	backpacks.clearself
		Allows players to clear own backpack
	backpacks.clearother
		Allows players to clear others backpacks
	backpacks.size.<size>
		Defines what size backpack to have. Must be a multiple of 9
Translations:
	clear-backpack-success
		Called when a backpack is successfully cleared
	you-dont-have-a-backpack
		Called when you don't have a backpack to open
	player-doesnt-have-a-backpack
		called when you try to access the backpack of someone who doesn't have one