iOS 5 brought with it a number of new features and improvements for iPad users, and one of the more curious among them was the ability to split the device’s software keyboard in two, allowing users to use both thumbs to type, as they do on iPhones or iPod touches. But did you know that this special keyboard also features unseen, hidden keys that can help you out if you’re used to hitting certain keys with certain thumbs? Indeed, tapping…