Refactor thread handling to fix OS X bug. On OS X, openL2CAPChannelSync registers events on the current thread's run loop, so Connect needs to be called on a thread that's going to do CFRunLoopRun; this was causing all Wiimote input to be ignored. Easiest way to do that is to use the Wiimote thread, and have Read call CFRunLoopRun to block on events, bringing OS X's Wiimote event loop in line with every other platform's. This also means that the thread can't be stopped and recreated by Prepare, so make Prepare notify it instead, which has the side effect of not making the GUI block on Prepare. (It would be nice if the GUI also did not block on searching for devices, because blocking the GUI is gross, but for now...)