Work on major bug EXT-3976 (Voice chat speaking indicators should only display...

Work on major bug EXT-3976 (Voice chat speaking indicators should only display when users are in the same voice channel)
-- implemented functionality to have voice indicator visible only for avatars in the same voice channel with agent
   All speacking indicators should be registered in LLSpeakingIndicatorManager to be provcessed for the voice channel.
   They should implement switchIndicator(bool) as reaction on voice state changing

--HG--
branch : product-engine