Added the listeners package in the common module to provide more unified support for listeners.
Refactored the worker implementation to use the new ListenerSupport class.
Added listener support in ClientManager.
Added listener support in WorkerCoordinator.
Moved some static classes in the ClientManager and WorkerCoordinator implementations out into their own files to keep the file size at a reasonable length.
Renamed method parameters in listener interfaces to be more consistent.
Added top-level listener support in the server module.
Added support for shutting down listener executors.
Merge branch 'master' of github.com:golvmopp/sdmapeg