Implement AudioWorklet version of Web Csound

[kunstmusik]

An implementation of AudioWorklet is now testable in Chrome Canary:

http://googlechromelabs.github.io/web-audio-samples/audio-worklet/
https://webaudio.github.io/web-audio-api/#AudioWorklet

The Faust project has already done research work into supporting AudioWorklet and have published examples at:

http://faust.grame.fr/modules-worklet/

[kunstmusik]

I added a development repo here:

https://github.com/kunstmusik/csound-audioworklet

to work on writing the AudioWorklet code. The repo has a pre-built Csound binary committed to repo to make development easier. Once a basic working version is done, plan is to move back in to csound/emscripten folder as an example.

[kunstmusik]

This is complete and work is in main repo now.