Send email notification when user is mentioned in Talk

[tigrrr]

Some users do not use the desktop client and can easily miss the notification on talk mentions. Option to send out email in such cases would be pretty easy to implement and verry, verry usefull for many. I'm surprised nobody has suggested this up to date.

The implementation is straight forward: in the Settungs/Activity, add a line with "User is mentioned in Talk" and the Mail/Stream checkbox.

Thanks for the support!