openInventory()
"opens" your inventory so you can move items around.
Returns a table with controls. (If gui is already open that will be used)

Controls:
  swapStack(slot1, slot2) simulates clicking slot1, then 2 than 1 again
  splitStack(slot1, slot2, amount) takes the stack, places *amount* in slot2 and puts stack1 back
  close() tell the server you "closed your inventory", things may act weird if you don't
  mapping - A table that tells you what all the slots are
    hotbar
    main
    boots
    leggings
    chestplate
    helmet
    offHand
    craftingIn
    craftingOut
  
You can craft in your 2x2 crafting like this
it's also possible to leave items in it as of now.