Working on simultaneous audio, video, and screensharing. New events
'localstream-screen' and 'remotestream-screen' added.
Minor changes and a little bit of documentation added.
Fixing problem with event names.
Fixing a typo error.
Always call createScreenStream.
Using 'screenConstraints'.
screenMediaConstraints fixed.
getRemoteStreamEventName modified.
Bug in getRemoteStreamName fixed.
Fixed a typo mistake.
Screensharing flag in mediaConstraints added.
Identify remote screensharing stream by the number of audio substreams.