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

After some back-and-forth, I think it's still better to keep markup in
templates (instead of having them directly inside the components)
becaues it makes it easier for people to modify Converse.js (at the
expense of some developer ergonomics).