So that components can use `listenTo`

it's annoying in overlayed view-mode where the user might be navigating
around the site.

Fixes #2091

This will allow setting different colors in themes where the controlbox
is a different background color from the chat view and other parts, such
as the "concord" theme.

to avoid re-rendering them when non-relevant properties change

so that you can see the shortname when you hover your mouse over an emoji.

before adding them to the message body

* Makes message with errors non-editable

as assignable affiliation when the current user is an admin.

https://xmpp.org/extensions/xep-0045.html#affil-priv

Show the actions dropdown on the right, like with other messages, and
don't wrap them.

Fixes #2067

by checking for the affiliation data on the probe response presence and
not on the occupant model (which might be created from a message and
therefore not yet have up to date affiliation data).

* elements where too large
* ugly drop shadow

instead just set the classes directly on the custom element

As far as I can tell, this fixes #1346 (or it was fixed already)

By registering a one-time event handler for a unique event name