In order to support XMPP authentication, we'll need the message
accompanying the error and carried by lib-jitsi-meet's
CONFERENCE_FAILED in the redux store. We already carry the message in
the redux action and we've got the error in the redux store.

fix(Filmstrip.js): Make sure the local thumbnail is there

fix(conference.js): Add message listeners only when chat is enabled

In order to accommodate the requirements of the work on supporting XMPP
authentication on mobile/react-native, make dealing with Dialog a
little more generic and a little easier.

Without dominant speaker in redux, the wrong user will be
selected after an unpin event.

Filmstrip only mode displays a device selection dialog that
does not have access to the redux/connect. However, the current
VideoTrack extends from AbstractVideoTrack, which assumes a
redux connection. The fix is to move video display logic into
a separate component and have device selection use that, while
the existing VideoTrack remains connected to redux but
uses the new video display component.

Don't require autofocus because that prevents the app from appearing in
Google Play Store for some devices.

Don't require camera for the same reason but also because camera/video
is not a mandatory feature of the app, it's merely likely very
desirable.

In Chrome M63 a warning is shown, permissions won't be automatically allowed
afterwards. Reference:
https://sites.google.com/a/chromium.org/dev/Home/chromium-security/deprecating-permissions-in-cross-origin-iframes

Setting this early makes us future proof, while working with current versions
too: Chrome < 63 gives an error because it doesn't understand the option and
Firefox seems to ignore it, so both continue to work as before.

The class ReflectiveOperationException used in ExternalAPIModule was
introduced in API level 19.

Based on work authored by Shuai Li <sli@atlassian.com>, Daniel Ornelas
<dornelas@atlassian.com>, and Lyubo Marinov <lmarinov@atlassian.com>.

Instead of going through the Avatar object, call the getAvatarURL
directly so that the code flows consistently use the participant
representation within redux.

In certain scenarios we do need to import files instead of features but
even then it is our coding style to not write the file extension.

We broke external_api.min.js by importing react/features/util which
imported react/features/base/lib-jitsi-meet.

1. To reduce the risks of such a breakage until we add
   external_api.min.js to the torture tests, import as little as
   possible in modules/API/external/external_api.js.
2. Use the global JitsiMeetJS on Web in react/features/base/util.

JitsiMeetViewListener is an integral part of the public API of Jitsi
Meet SDK for Android. Utilize it in the Debug configuration of the Jitsi
Meet app for Android in order to increase (1) awareness of API breakages
and (2) API coverage.

The same goes for JitsiMeetViewDelegate in Jitsi Meet SDK and app for
iOS.

The error is stored in the redux store in base/config so other components can
consult it. It is also broadcasted as a new event in the external API for the
SDK.

JitsiMeetViewListener currently has methods of one and the same pattern
so adding new methods i.e. events i.e. redux action types is a question
of repetition in the Java source code. Speed up the support of new
events by trying to deal with them in a generic way.

The same goes for JitsiMeetViewDelegate.

- Remove references to the model ContactList.
- Replace ContactListView with an empty element for attaching
  the React Component ContactListPanel, which has the same
  features as the old ContactListView.
- Create new selector for getting non-fake participants for
  ContactListPanel's props.
- Create a ParticipantCounter component to place in the contact
  list button. Previously ContactListView updated that but now
  it's a react component hooked into the participant state.
- Remove pub/sub that was used only by ContactListView.

Implement a React Component which displays children as an overlay of
local video. The WelcomePage implemented such a component inside of it
among other WelcomePage-specific logic so I split
LocalVideoTrackUnderlay out of it. The new Component is used on the
BlankPage which may be displayed in the future not only when the
WelcomePage is disabled but also when there are long running network
requests, for example.

This only helps iff there is a short transient network error which prevents the
configuration from being loaded. In such case, use the cached version in
localStorage, which may not match the shard, but it's (probably!) better than
nothing.

In case there is no Internet connectivity, an error will be produced as soon as
the XMPP connection is attempted anyway.