Accessing the undo command on the iPhone and iPod touch is as easy as shaking the device… but the iPad is decidedly less-easy to move easily, and as such, shake-to-undo features are even less common on the iPad than they are on its smaller siblings. Luckily, Apple baked an undo feature right into the iPad’s keyboard, saving you from looking like a crazy person who violently shakes their gadgets in public. To access it, simply bring up…