or: "Shut up, StreamLabs"

Automatically silence the StreamLabs dashboard notifications. Will suppress the number in the tab title, and hide the red number on the notifications button. If you wish to see the actual notifs, they will still be there, waiting for you. Note that the bell will still "shake", so if you deliberately choose to look at it, you can see that there are notifications waiting for you (but it's not distracting).

Also tweaks the Twitch chat box "copy to clipboard" behaviour, making it more chat-like and less "hey let's show all those badges and stuff".

"Mute" icon from Font Awesome via https://www.iconfinder.com/icons/1608871/bell_slash_icon

To update:

1. Bump the version number in the manifest
2. Run make to create/refresh the zip file
3. Go to https://chrome.google.com/webstore/devconsole/ and upload the new file.