[qmf] When messageListModel limit changes add more messages to model ins...

...tead of full refresh.
What about if we have 20 messages, limit is 20 and we get 2 new messages, we want those to shown in the list, if we don't remove 2 of the existent ones there would be no space. One optimization that could be done here is check if the index of the coming message is bigger than limit and in that case discard it before insertion, but for others inserting in the middle or top we need to remove in this case to ensure we have all the time most recent messages.