Fixes trading materials with custom spritesheets not using the custom spritesheet
Closes #1140 (closed).
Imitates the logic in the inventory UI, but for the trade window: If a custom spritesheet is set, use that, otherwise, use items.png
. If there's no custom spritesheet, check if its a material/quest/consumable/skin and set the spritesheet accordingly.
The old logic would check if it was a material and if so, use the materials
spritesheet, even if the item had a custom spritesheet.