Shop UI Rework

[Houdini111]

The current shop interface is somewhat clunky and does not lend itself well to expansion.

I think that having the inventories multiple List Boxes (with a "column" for name, quantity, and value) tied together (when one is selected, edit the current selection of it's siblings) would allow for a cleaner interface.

I plan to look into building this after the things I currently have assigned (Debug menu and then dungeon generation settings)