Print a more detailed message on CHAT_CHANGE_PEER_DEL, so a user isn't confounded by the change of peer numbers.

On deleting the last peer, it's just a delete.
On deleting any other peer, the last peer is moved into that space, gaining a different number.
Print that detail where appropriate.
Merge pull request #665 from FullName/peerdel-ntox-feedback

Print a more detailed message on CHAT_CHANGE_PEER_DEL, so a user isn't confounded...