Handle the audio stream playback with a web worker in the browser

[fakufaku]

Currently both the graphics and the audio are handled in the same thread in the browser. When there is a lot of audio streaming this could be a problem. We could create a web worker that takes care of getting the audio from the websocket, resample it and plays it back.

It the only communication needed with the main thread is:

• set origin of audio stream (python code server or ws-audio)
• play
• stop

what needs to be decided is how to handle configuration changes