Add moderation rules:
* You can apply rules in the settings.toml to enforce moderator restrictions on
certain users, e.g. to force their camera to always be NSFW or bar them from
sharing their webcam at all anymore.
Chat UI improvements around users blocking admin accounts:
* When a main website block is in place, the DMs button in the Who List shows
as greyed out with a cross through, as if that user had closed their DMs.
* Admin users are always able to watch the camera of people who have blocked
them. The broadcaster is not notified about the watch.
New operator commands:
* /cut username: to tell a user to turn off their webcam.
* /unmute-all: to lift all mutes on your side, e.g. so your moderator chatbot
can still see public messages from users who have blocked it.
* /help-advanced: moved the more dangerous admin command documentation here.
Miscellaneous fixes:
* The admin commands now tolerate an @ prefix in front of usernames.
* The /nsfw command won't fire unless the user's camera is actually active and
not marked as explicit.
