[OMEMO] Warn about messages from untrusted peers
If a contact has a new key, which is not trusted yet, its messages show up in the same way as trusted messages. It would be great if they were marked in some way.
A common scheme of verifying new keys is to send the new key from a verified device. With the current behavior it's easy to fool the other party that the key was sent from a verified device, especially that there's no easy way to check the origin from the chat window.