We now prevent these variations:
* <hr/>
* <hr />
* <br/>
* <br />
We could enforce similar consistency for other void
tags, if we wished, but these two are particularly
prevalent.
We used to put the user's email in a value, which was
redundant (we could find the value from
our parent's label) and brittle (would break
on email changes).
Now the DOM's a bit slimmer and more robust.
Also note that we now deal with user_ids, not emails,
in the call stack until we hit the "edge" and convert
to emails for the server.