Add display name getter

storage/itemstack.lua

@@ -108,6 +108,10 @@ function ItemStack:isEmpty()
   return self.count == nil or self.count == 0
 end
 
+function ItemStack:getDisplayName()
+  return self.displayName
+end
+
 function ItemStack:hasChanged(listObj, thorough)
   local listItem = listObj[self.slot]
   if listItem == nil or listItem.name ~= self.name or listItem.count ~= self.count then