Represent user power level in a room by a red bar at the bottom of his avatar image. The width of this bar depends on the power level.

Make the intro bit a separate section rather than have a 'quick start' section that only tells you how to get started half way through.

No need to test is_presence_visible in _start_polling_local because we know it will be by when it's called

That was a breaking db change. You need to recreate the databases. (In reality, it's enough to just run the im.sql through your db and change the schema version)