In order to help control traffic over the websocket, a subscription feature has been added:
* A config option, `enableMessengerSubscriptions` has been added
* When true, the MessengerBase class will assume that any message sent using the `PostStatusMessage` that has a valid client ID wants to send any subsequent unsolicited updates to that same client
* The client's ID will be added a list of subscribed client IDs
* Any subsequent messages sent using the `PostStatusMessage` methods that have a null clientId will ONLY be sent to subscribed clients
* When a client disconnects, it will be removed from the list of subscribed clients
This should cut down drastically on the traffic to the UI, especially when combined with requesting partial status updates from a device rather than the entire state.
In order to solve some dependency issues that keep cropping up, MC
should be moved back into the Essentials repo and loaded automatically
on startup. This will allow for all plugins that use the MC Messengers
library to use the same version without fear of overwriting a dll due to
loading of plugin libraries.
