order so new comments on notes bubble to the top

now we get all messages so we can check pos with any comments that have
been made on a note also show the number of comments

see https://trello.com/c/LyKQTCew
and https://trello.com/c/p8C2zLlJ
1. If there is a `note.parentmessage`, the sort function will return nothing? If you always expect the messages to be "notes" maybe remove the `if` statement, or return something (like the message date)?

2. The comment on this function could be something more explicit like "Sort 'Notes' by the most recent date between the note itself and the comments attached to it, if any"?