Don't notify users by phone notification if they were recently active on a desktop

[veryjos]

I'm often chatting at my desktop and will get notifications on my phone while active in chat. Toastie, please.

[mdkozlowski]

░░░░░░░░░░░░▄▄
░░░░░░░░░░░█░░█
░░░░░░░░░░░█░░█
░░░░░░░░░░█░░░█
░░░░░░░░░█░░░░█
███████▄▄█░░░░░██████▄ ▓▓▓▓▓▓█░░░░░░░░░░░░░░█ ▓▓▓▓▓▓█░░░░ Valve, ░░░░░█ ▓▓▓▓▓▓█░░░░Add This░░░░█
▓▓▓▓▓▓█░░░░Please!░░░░░█ ▓▓▓▓▓▓█░░░░░░░░░░░░░░█ ▓▓▓▓▓▓█████░░░░░░░░░█
██████▀░░░░▀▀██████▀