Bukkit

• Changed the "copy tag" from a tilde preceding the title of the book to [COPY] following the author of the book.
• Removed the possibility of a legitimate book not being able to be sold to a villager (usernames cannot have bracket characters).
• Added checks to prevent a book from being tagged as a [COPY] more than once.
• Fixed bug where having a copied written book in first hot barslot would result in any clicks in the villager's first slot to print the "unable to sell copies" message

* RIght-clicking a frame to obtain a copy of a book also rotates the book inside the frame. [Minor visual]