Fixes Hotbar Items sometimes not appearing in the inventory
Fixes visual glitches where panel items sometimes appear outside a panel after it is close
Adds a custom material item book= <Author>, similar to the lore, using 'write' will be pasted in the book
In the panel row: section, if instead of entering a number an InventoryType is entered, such as HOPPER, the panel will inherit that type of GUI. Not all InventoryTypes will work, and if you use the InventoryType LECTERN and set the item slot '0' to a book=, it will create a book GUI.