#330 Additional item (charges) work

- [x] Items with a charge count (not a physical stack of items) will now count down their charges to 0 and display 'This item is out of charges.' - [x] Items with an actual stack amount (eg. stack count is larger than 1) will remove an item with each 'use' down to 0 which removes the final item in the stack. - [x] display_charges is no longer required for the "use" function to be called (before we were decrementing display charges when the "use" function was called, which was always after 1). Now rely on the item->details.count