fix: Dispatcher::dispatch should return mixed (#31)

We have no idea what the method returns, so `mixed` is the most appropriate return type

lib/Dispatcher.php

@@ -58,7 +58,7 @@ public function __construct($target, $delimiter = '->')
      * Calls the appropriate method handler for an incoming Message
      *
      * @param string|object $msg The incoming message
-     * @return Result|void
+     * @return mixed
      */
     public function dispatch($msg)
     {