If no tool was involved in the creation of a bookshelf pickup (e.g. explosion), the server would crash due to a missing nullptr check. Removed the IsTool check completely, since we don't use it elsewhere, and vanilla doesn't do such checks either.
* Updated BookShelves Drop Behaviour As described here : https://minecraft.gamepedia.com/Bookshelf#Loot * Update src/Blocks/BlockBookShelf.h * Update CONTRIBUTORS