Up until now we relied on implicit loading of middlewares and reducers, through
having imports in each feature's index.js.

This leads to many complex import cycles which result in (sometimes) hard to fix
bugs in addition to (often) breaking mobile because a web-only feature gets
imported on mobile too, thanks to the implicit loading.

This PR changes that to make the process explicit. Both middlewares and reducers
are imported in a single place, the app entrypoint. They have been divided into
3 categories: any, web and native, which represent each of the platforms
  respectively.

Ideally no feature should have an index.js exporting actions, action types and
components, but that's a larger ordeal, so this is just the first step in
getting there. In order to both set example and avoid large cycles the app
feature has been refactored to not have an idex.js itself.

This refactors all handling of audio-only and last N to 2 features in preparation
for "low bandwidth mode".

The main motivation to do this is that lastN is a "global" setting so it helps
to have all processing for it in a single place.

🔥🔥🔥

Using anything non-serializable for action types is discouraged:
https://redux.js.org/faq/actions#actions

In fact, this is the Flow definition for dispatching actions:

declare export type DispatchAPI<A> = (action: A) => A;
declare export type Dispatch<A: { type: $Subtype<string> }> = DispatchAPI<A>;

Note how the `type` field is defined as a subtype of string, which Symbol isn’t.

BaseApp does all the heavy-lifting related to creating the redux store,
navigation, and so on.

App currently handles URL props and actually triggering navigation based on
them.

On Android we go into "immersive mode" when in a conference, this is our way of
being full-creen. There are occasions, however, in which Android takes us out of
immerfive mode without us (the application / SDK) knowing: when a child activity
is started, a modal window shown, etc.

In order to be resilient to any possible change in the immersive mode, register
a listener which will be called when Android changes it, so we can re-eavluate
if we need it and thus re-enable it.

* ref: Restructures the pinned/unpinned events.

* ref: Refactors the "audio only disabled" event.

* ref: Refactors the "stream switch delay" event.

* ref: Refactors the "select participant failed" event.

* ref: Refactors the "initially muted" events.

* ref: Refactors the screen sharing started/stopped events.

* ref: Restructures the "device list changed" events.

* ref: Restructures the "shared video" events.

* ref: Restructures the "start muted" events.

* ref: Restructures the "start audio only" event.

* ref: Restructures the "sync track state" event.

* ref: Restructures the "callkit" events.

* ref: Restructures the "replace track".

* ref: Restructures keyboard shortcuts events.

* ref: Restructures most of the toolbar events.

* ref: Refactors the API events.

* ref: Restructures the video quality, profile button and invite dialog events.

* ref: Refactors the "device changed" events.

* ref: Refactors the page reload event.

* ref: Removes an unused function.

* ref: Removes a method which is needlessly exposed under a different name.

* ref: Refactors the events from the remote video menu.

* ref: Refactors the events from the profile pane.

* ref: Restructures the recording-related events.

Removes events fired when recording with something other than jibri
(which isn't currently supported anyway).

* ref: Cleans up AnalyticsEvents.js.

* ref: Removes an unused function and adds documentation.

* feat: Adds events for all API calls.

* fix: Addresses feedback.

* fix: Brings back mistakenly removed code.

* fix: Simplifies code and fixes a bug in toggleFilmstrip

when the 'visible' parameter is defined.

* feat: Removes the resolution change application log.

* ref: Uses consistent naming for events' attributes.

Uses "_" as a separator instead of camel case or ".".

* ref: Don't add the user agent and conference name

as permanent properties. The library does this on its own now.

* ref: Adapts the GA handler to changes in lib-jitsi-meet.

* ref: Removes unused fields from the analytics handler initializaiton.

* ref: Renames the google analytics file and add docs.

* fix: Fixes the push-to-talk events and logs.

* npm: Updates lib-jitsi-meet to 515374c8d3.

* fix: Fixes a recently introduced bug in the google analytics handler.

* ref: Uses "value" instead of "delay" since this is friendlier to GA.

* ref(analytics): centralize all event names

* squash: fix typo and alpha ordering

* squash: rename file to AnalyticsEvents to parallel lib-jitsi-meet

ESLint 4.8.0 discovers a lot of error related to formatting. While I
tried to fix as many of them as possible, a portion of them actually go
against our coding style. In such a case, I've disabled the indent rule
which effectively leaves it as it was before ESLint 4.8.0.

Additionally, remove jshint because it's becoming a nuisance with its
lack of understanding of ES2015+.

Simplify the code by using a bitfied instead of a couple of boolean flags. This
allows us to mute the video from multiple places and only make the unmute
effective once they have all unmuted.

Alas, this cannot be applied to the web without a massive refactor, because it
uses the track muted state as the source of truth instead of the media state.

The behavior can be triggered with the toggleAudioOnly action, which is
currently fired with a button.

The following aspects of the conference will change when in audio only mode:

- local video is muted
- last N is set to 0 (effectively muting remote video)
- full-screen mode is exited
- audio mode is set to "audio chat" (default output is the earpiece)
- the wake lock is disengaged

One aspect not handled in this patch is disabling the video mute button while in
audio only mode. The user should not be able to turn back video on in that case.

This is in preparation for an upcoming "audio only mode" feature. Setting last N
will also be required for it, so this patch factors out the action and makes it
public so other modules can reuse it.

In addition, if the value is set to undefined the configured default value (or
-1 if absent) is picked.