Fix logic around dealing with failed commands.

Use local domain socket. Attempt to keep alive and deal with connection errors.

Attempt to retry connecting in case mpd isn't up yet. Toggle play/stop.

Use 'run' instead of 'send' (otherwise would need to use 'recv'). Put mpd functions outside lock. Implement all buttons.

Test play/pause; really needs to be outside lock.

Start with wiringPi and libmpdclient