Starts this bot in a separate thread. Therefore, this call is non-blocking.

        It will listen to all new inbox messages created.

def start(self):
        """
        Starts this bot in a separate thread. Therefore, this call is non-blocking.

        It will listen to all new inbox messages created.
        """
        super().start()
        inbox_thread = BotThread(name='{}-inbox-stream-thread'.format(self._name),
                                 target=self._listen_inbox_messages)
        inbox_thread.start()
        self._threads.append(inbox_thread)
        self.log.info('Starting inbox stream ...')