update homekit UI when event happens outside homekit

[anthonywebb]

I've been hunting through your code to figure out how you ended up getting around the issue where someone changes state, but not from within the homekit UI (say someone presses a button on the wall). Right now all is well with my plugin so long as everyone uses homekit to toggle the lights, once a wall button is pressed everything is out of sync. My code (for CBus) very closely models this plugin https://github.com/YahavGB/homebridge-mox

[cflurin]

have a look here: https://github.com/cflurin/homebridge-mqtt/blob/master/lib/accessory.js

Accessory.prototype.save_and_setValue

and here: https://github.com/KhaosT/HAP-NodeJS/blob/master/lib/Characteristic.js

 * @event 'set' => function(newValue, callback(err), context) { }
 *        Emitted when someone calls setValue() on this Characteristic with a desired new value. If there
 *        are any listeners to this event, one of them MUST call the callback in order for this.value to
 *        actually be set. The `context` object is whatever was passed in by the initiator of this change
 *        (for instance, whomever called `setValue`).