Refactor item handling.

[Saint Wish]

Currently all items in your inventory is spawned in the world at 0,0,0 which contributes to the entity limit. We should find a way to only spawn the items that are being used and make the items in the inventory just be data instead of being spawned entities, this would probably allow players to have a lot more items in their inventory and save up on used entity limit. The galat chest items are not handled this way though.

We should also investigate a way to convert string names of items to some kind of short hand like an ID and way to convert them back to script name so players won't loose any items by us changing the script name.

[Saint Wish]

Maybe one way can redo item handling is to assign each item once angelscript is out with a numbered ID, so then we can just handle the item as a vector or an map with with a list of numbers instead of a string.