Tracking formatting changes UI
We need to think of what the UI is gonna be for styling changes, both inline and block-level.
The challenge is to have them be consistent with the current design, but at the same time different enough so that they wouldn't be confused for a tracked addition.
On a functional level, we currently have two types of changes ("add" and "delete"), so we'd probably need to introduce more, so that on accepting something, only the style is removed.