iBooks 3 introduces a new Purchased Books feature that gathers all of a user’s iBooks that have been purchased from the iBookstore into a single collection for quick and easy access, allowing books not already on the device to be easily downloaded from iCloud at the tap of a finger. For users who may not want to see some or all of their purchases right in the iBooks app, however, the good news is that you can either turn this feature off entirely,…