Rename setStateProperties and setStateProperty to assign and set,
respectively. Inspired by Object.assign, _.assign, and _.set.

When a conference is to happen in a domain which is not the defaut, its config
is loaded and set. As part of this process, lib-jitsi-meet is disposed. Because
disposing is asynchronous, events happen in this sequence:

- set new config
- dispose lib (which effectively wipes the config)
- init lib

This results in the library to be initialized without the loaded config, which
was lost. This commit fixes that by delaying setting the config and
re-initializing the library until it was disposed.

The error raised by JitsiMeetJS.init() is already in the state of
features/base/lib-jitsi-meet so it's not a good design to store the same
error in the state of features/unsupported-browser.

The toolbar's mute buttons depict respective features/base/media states.
However, (un)muting is practically carried out by features/base/tracks.
When the mobile app enters a conference configured to invite the joining
participant to mute themselves, the tracks would be muted but the
toolbar's mute buttons would not reflect that.

As an intermediate step on the path to merging jitsi-meet and
jitsi-meet-react, import the whole source code of jitsi-meet-react as it
stands at
2f23d98424
i.e. the lastest master at the time of this import. No modifications are
applied to the imported source code in order to preserve a complete
snapshot of it in the repository of jitsi-meet and, thus, facilitate
comparison later on. Consequently, the source code of jitsi-meet and/or
jitsi-meet-react may not work. For example, jitsi-meet's jshint may be
unable to parse jitsi-meet-react's source code.