Allow incompatible enchantments to be overwritten by enchanted books.

Incompatible enchantments (ex. Smite and Sharpness) should be able to be overwritten by the preceding enchanted book in an anvil. This currently exists in the form of combining tools together, the second tool takes priority over the incompatibility. If it exists in that form, I believe it should be made easier with the use of an enchanted book.