Option to email an @mentioned user

[bdharrington7]

It would be great to have the option to have an @mentioned user receive an email when they are mentioned. In my use case, there are some members that spend some long periods of time away from the forum, and I would like to have a mention notify them in their inbox. Currently the only (core supported) ways of notifying a member through e-mail is by replying in a thread that they've commented in or started.