Prepare for React 16.

When do we need tracks?

- Welcome page (only the video track)
- Conference (depends if starting with audio / video muted is requested)

When do we need to destroy the tracks?

- When we are not in a conference and there is no welcome page

In order to accommodate all the above use cases, a new component is introduced:
BlankWelcomePage. Its purpose is to take the place of the welcome page when it
is disabled. When this component is mounted local tracks are destroyed.

Analogously, a video track is created when the (real) welcome page is created,
and all the desired tracks are created then the Conference component is created.
What are desired tracks? These are the tracks we'd like to use for the
conference that is about to happen. By default both audio and video are desired.
It's possible, however, the user requested to start the call with no
video/audio, in which case it's muted in base/media and a track is not created.

The first time the app starts (with the welcome page) it will request permission
for video only, since there is no need for audio in the welcome page. Later,
when a conference is joined permission for audio will be requested when an audio
track is to be created. The audio track is not destroyed when the conference
ends. Yours truly thinks this is not needed since it's a stopped track which is
not using system resources.

* feat(notifications): implement a react/redux notification system

* squash into impl explicit timeout, style

* ref(notifications): convert toastr notifications to use react

* ref(toastr): remove library

* squash into conversion: pass timeout

* squash into clean remove from debian patch

The functions need not return anything, or it will be dispatched as another
action.

* fix(filmstrip-only): vertically align center the toolbar

Use top 50% to position the toolbar's top at the vertical center
of the iframe. Then use transform 50% to move the toolbar itself
up 50% so its middle matches the middle of the iframe.

* squash: toolbox should center with filmstrip

The files styles.js are used (pretty much) on React Native only and each
of them exports 1 name. Export it as default to cut down on source code.

We've had Filmstrip & LargeVideo React Components on mobile/React Native
from the start. We didn't have them on Web (because the rewrite in React
is not complete yet). However, that led to differences in the React
Component Conference on Web and mobile. In an effort to get closer to
merging the React Component Conference on Web and mobile, introduce the
React Components Filmstrip & LargeVideo on Web even if a minimal
render-only form at this time.

The video status labels, which include recording and hd status,
have been moved back to the top left while in vertical filmstrip
mode. The following had to be done:
- Remove styling to move the labels to the bottom left
- For VideoStatusLabel, move filmstrip remote video count, toggle
  state, and 1:1 state into redux.
- Use middleware to emit out to the Recording label when the
  filmstrip changes.
- Create an empty Filmstrip file for web and identify the existing
  Filmstrip component as native.

The 1:1 call UI and vertical filmstrip act on remote videos
while leaving local video alone. To facilitate acting only on
remote videos, place remote videos into their own container element.

In its current implementation, the VideoStatusLabel shows HD based on peer
connection stats. These stats will be available on temasys browsers soon but
will remain unavailable on Firefox, which does not collect height/width stats.
To support VideoStatusLabel showing cross-browser, move the high-definition
detection out of stat sniffing and instead check the video element itself using
an interval in LargeVideoManager. (An interval was used because the temasys
video object does not support the onresize event.) Also, add a cleanup path from
conference.web to LargeVideoManager to remove the interval.

Make 'Add jwt module to react' work on mobile.

Move the HD label into the newly renamed VideoStatusLabel
component. That way it cannot be possible for the audio only
label and the HD label to display simultaneously.

Audio only mode can be used to save bandwidth. In this mode local video is muted
and last N is set to 0, thus disabling all remote video.

When this mode is enabled avatars are shown.

We seemed to be using the names "film strip" and "filmstrip" (and,
consequently, their source code-conscious forms such as film-strip,
FilmStrip, etc.) In order to comply with our coding style which requires
a consistent one name for a given abstraction, choose one name and
rename the uses of the other name.

Wikipedia has a definition of a "filmstrip", I couldn't find a "film
strip". I guess our abstraction can be seen as what's described there.
When I google "film strip", I get results about "filmstrip" at the top.
That's why I chose "filmstrip".

Certain uses of "film strip" such as interfaceConfig.filmStripOnly and
in the external API I left untouched in an attempt to preserve
compatibility.

I wasn't sure whether CSS was tangled in compatibility so I made a
choice and renamed there was well.

Moves native dialogs to use dialog container. Implements native Dialog that uses react native Prompt.

Split language detectors to be web/native dependent. Take care of strings that contain html.

Looks like Android gets confused as to what surface to blit when we hide or
show toolbars. Setting a border on the container, seems to force the entire
area to blit properly.

Other attempted approaches, with no success:
- zIndex of -100
- width and height of 0
- opacity of 0 and setting 'disabled' on touch containers

This patch applies the workaround in the welcome page and conference containers.

When callstats is not configured hide the button.

Until we make a decision on access modifier hints and adopt a respective
coding style, consistency is king.

Recently, we reimplemented the watermarks in React. Unfortunately, we
didn't take into account film strip-only mode.

Additionally, we duplicated watermark-related source code on the Welcome
and Conference pages.