Silk Touch should override Fortune enchanted tools

Using an enchanting table is often not worth it with tools as you are likely to get a level of Fortune when doing a max level enchantment. Fortune is great and all but realistically most players only need one Fortune III pickaxe which they will only use at their bases. Many times a player will get stuck with a Fortune pickaxe they don't need another of. Make it so that applying a Silk Touch book to a Fortune enchanted tool replaces Fortune while applying Silk Touch. This however should keep other enchantments such as Unbreaking.