Pings everyone in chat with an @, with an optional message first (=massping stream starting!). Uses Twitch’s viewer list where the bot is a mod, otherwise people who chatted in the last 3 hours. To stay within Twitch’s spam rules it runs at most once every 5 minutes per channel and pings up to 150 people, and leaves out bots and people who used =forgetme.
=massping [message]