Instead of creating an instance of a protocol per user and storing state there, we just have the protocol implementations take in all of the state they should need in processMessage(), and store them all globally (with some wrappers to make it easier to handle this). This makes things slightly cleaner (and probably also helps memory usage, since we now don't need to create protocol instances as soon as a user connects/swaps, and they don't need to be garbage collected since they are held in the manager.)
