Move listen methods out of Client and into MQTT class

Make MQTT class / `Listener` public

examples/removebot.py

@@ -1,23 +1,19 @@
 import fbchat
 
-
-class RemoveBot(fbchat.Client):
-    def on_message(self, author_id, message_object, thread, **kwargs):
-        # We can only kick people from group chats, so no need to try if it's a user chat
-        if message_object.text == "Remove me!" and isinstance(thread, fbchat.Group):
-            print("{} will be removed from {}".format(author_id, thread))
-            thread.remove_participant(author_id)
-        else:
-            # Sends the data to the inherited on_message, so that we can still see when a message is recieved
-            super(RemoveBot, self).on_message(
-                author_id=author_id,
-                message_object=message_object,
-                thread=thread,
-                **kwargs,
-            )
-
-
 session = fbchat.Session.login("<email>", "<password>")
 
-remove_bot = RemoveBot(session)
-remove_bot.listen()
+listener = fbchat.Listener.connect(session, chat_on=False, foreground=False)
+
+
+def on_message(event):
+    # We can only kick people from group chats, so no need to try if it's a user chat
+    if not isinstance(event.thread, fbchat.Group):
+        return
+    if message.text == "Remove me!":
+        print(f"{event.author.id} will be removed from {event.thread.id}")
+        event.thread.remove_participant(event.author.id)
+
+
+for event in listener.listen():
+    if isinstance(event, fbchat.MessageEvent):
+        on_message(event)