Fix JitsiMeetJS option disableAudioLevels

JitsiMeetJS#init accepts an options object in which the property
disableAudioLevels may optionally be defined and is meant to disable RTC
statistics related to audio levels. Unfortunately, the option was used
in a boolean expression which ignored the value of the option and thus
effectively rendered it unused.

Added ability to notify about available media device list changes

Report the error as object to callstats.

Removes fabricSetupFailed.

Adds NWJS to the list of browsers capable of changing the input devices

Fixes issue with callstats confID

Updates callstats error reporting

Fixes issue with not completing promise for remove/add track and conference leave

Remove unused connectionquality module

Fix off recording state handling

Fix jibri presence initial state

Fixes chrome undefined JS error

Prepare for React Native

Since (1) half of the disco uses check whether the feature in question
is supported, (2) the other half appears to not absolutely require
disco, and (3) disco needs to be explicitly included/required in order
to be supported, make disco completely optional.

Since half of the Settings functions check whether localStorage is
supported, adds the check to the other half to make localStorage
completely optional.

The function filter_special_chars does not have to throw a TypeError
when its argument text is null or undefined because (1) it can be argued
that neither of these two contains special characters and (2) it is much
more convenient to have the check in the function in question rather at
its multiple call sites.

Fix missing hidden domain problem

Don't rely on JitsiMeetJS being global

While we have JitsiMeetJS defined as a global variable in Jitsi Meet, it
doesn't sound like an absolutely necessary and beautiful requirement
inside the library itself.