Fixes #2126

(i.e. not on reconnection)

the first time it's opened

Changes how rich message markup is generated and kept track of.
We now have a MessageText class which subclasses String and which keeps
track of the rich markup associated with the message.

Wait for emojis to be initialized before parsing MAM messages

- Declaratively render the emoji picker dropup
- Got rid of converse-emoji-views
- Adapt OMEMO to the new buttons stuff
- Make emojis json global, to try and speed up tests
- omemo: Move functions to the top of the module

which throws and error and causes tests to fail

Created a web component registry and exports components as modules in order to facilitate their customization

So that it is the same size as in the 'fullscreen' view mode

to overcome cross-site restrictions on using the `use` attribute of the `<svg>` element.

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.