Updating react-native-fast-image brings a couple of interesting changes:

- onLoad is not called for cached images (reported and ignored upstream)
- load progress not working if component not displayed (on Android)

In order to fix this, a combination of 2 approaches was used:

- onLoadEnd / onError are used to detect if the image is loaded
- off-screen rendering is used on Android to get progress events

While implementing the above, yours truly noticed the complexity was increasing
way too much, so some extra refactoring was also performed:

- componentWillReceiveProps is dropped
- an auxiliary component (AvatarContent) is used for the actual content of the
  Avatar, with the former passing the key prop to the latter

Using the key prop ensures AvatarContent will be recreated if the URI changes,
which is not a bad idea anyway, since the new image needs to be downloaded.

* Replaces smileys and the logic of replacing links/emails.

Now using react-emoji-render and react-linkify.

* Fixes heart emoji.

It is known that current implementation doesn't work with ascii emojis that contain < or >, like >:( >:-( </3 <\3 <3. Making those work may bring some xss issues.

* Adds '_blank' and 'noopener noreferrer' to the replaced links.

* Fixes package-lock links (http vs https).

* Fixes comments.

The upstream package has been unmaintained for 2 years now, and making the litle
changes needed as React Native needs them is getting old. The actual
funcionality is a couple of one-liners plus tons of boliterplate, which gets
reduced by quite a bit if we just embed it. So here it goes.

They are part of the Jitsi font now, there is no need to load them from
FontAwesome.

It doesn't seem like videoTrack needs to be set onto state
if it can be accessed directly from props. Removing the state
automatically removes the deprecated componentWillReceiveProps.

Remove caching of calculated styles, thereby removing
componentWillReceiveProps, by passing in base styles
and passed in styles when rendering.

Filmstrip remote thumbnails display under certain conditions, as
defined in filmstrip/functions.web.js. Previously the raw
participant count was used, which included fake participants.
Using the selector getParticipantCount excludes fake participants,
causing YouTube thumbnails to remain hidden in a 1-on-1 call.

- Derive the showOverlay state. When the sidebar should be hidden,
  the internal showOverlay state should remain true until the
  animation hides it. When the sidebar should show, the showOverlay
  state should become true immediately.
- Use PureComponent to prevent additional animation triggers
  instead of explicitly checking changes to the "show" prop.

Based on react-native docs, looks like animations should be
started after mount. Updating animation states I'm not certain
on so I moved it to componentDidUpdate and tested with the
live streaming label to ensure the component still animated fine.

To kill componentWillMount, call destroyLocalTrack after mount.
Navigation to the blank page was synthetically forced and no
UI issues were noticed, possibly because destroyLocalTrack may
already be async so destruction may already have been occurring
after mount.

Per react migration docs, initially fetching external data is
recommended to be done in componentDidMount.

For the most part the changes are taking the "static propTypes" declaration off
of components and declaring them as Flow types. Sometimes to support flow some
method signatures had to be added. There are some exceptions in which more had
to be done to tame the beast:
- AbstractVideoTrack: put in additional truthy checks for videoTrack.
- Video: add truthy checks for the _videoElement ref.
- shouldRenderVideoTrack function: Some component could pass null for the
  videoTrack argument and Flow wanted that called out explicitly.
- DisplayName: Add a truthy check for the input ref before acting on it.
- NumbersList: Move array checks inline for Flow to comprehend array methods
  could be called. Add type checks in the Object.entries loop as the value is
  assumed to be a mixed type by Flow.
- AbstractToolbarButton: add additional truthy check for passed in type.

* feat(welcome-page): Redesign.

* Style adjustments.

It doesn't seem to work properly.

That is only required if we'd want our backend to authenticate on behalf of our
users. If the app is to authenticate directly it's not needed.