Introduce JingleSessionState constants. Make the invalid JingleSession
rejection an explicit action taken by the JitsiConference.

Our JSHint configuration is not extensive and we have excluded multiple
files from linting. Additionally, we have seen JSHint to be unable to
parse newer ECMAScript features such as the object spread operator
(proposal).

On the other hand, we have seen ESLint to beautifully work on React and
React Native source code in addition to ES2015 and later. Introduce
ESLint alongside JSHint as an intermediate step to eventually switching
from JSHint to ESLint.

As our source code does not fully follow even the JSHint rules we have,
it is very difficult to introduce ESLint with many rules. At the
beginning, introduce it with as little rules as possible. Morever,
ESLint is able to automatically fix certain rule offenders so once we
have ESLint merged we can incrementally add new rules while keeping our
commits' modification on as little subjects as possible.

JitsiConference passed in the constructor and adding all events happen inside the feature.

By default talk while muted detection is disabled.

The timeout will be configurable though
'peerDisconnectedThroughRtcTimeout' conference config option. It has
not been document in the public API on purpose.

The event is triggered when the notification about the user's connection
status change arrives from the JVB.

This currently fixes problem for participants joining in a room with other participants and trying to send initial value of selected local participant will throw an error. And fixes a potential problem if the UI can select participants before their video is available, before session initiated, can make local state with jvb inconsistent. Also if we want to have multiple selected endpoints or pinned participants and this is done before session-initiate caching should be done before creating data channel (currently selecting multiple is not possible).

Use 'sendToAll' for 'session.restart' and 'session.terminate' events.

Not doing so will cause issues when trying to mute after
'session-terminate', because the PeerConnection is closed and should not
be used anymore.

When call ends the PeerConnection is closed and the SSRCs stored in
the local track will not match those assigned the PeerConnection when
it's reopened for new session. This will confuse SSRC replacement logic.
We need to reset those SSRCs and re-register 'ssrcHandler' listener to
get the new ones.

The event is triggered when Jicofo sends 'session-terminate' and our
PeerConnection is closed.

Also adds a safe check if there was no regionInfo to skip reporting cross-region.

removed white space
redid the hooking of the Transcribing module to JitsiConference
redid the exposing of the Transcribing module to JitsiMeetJs