HTML5 live update

An update for this support.

  1. It needs pthread support enabled. This means SharedArrayBuffer support - https://caniuse.com/#feat=sharedarraybuffer shows that only certain browsers support this.
  2. You need to run a proxy application in the background (ie tools/websocket_to_posix_proxy/ in emscripten) to allow websocket data to be converted to socket data. We can supply this (I have bulit this for windows, not mac or linux, but it is open source). I have only got this to partially work.
  3. It would have to be a special build that is for development purposes only, mainly due to point #1.

If these things are ok we can release a version with this stuff included, though I have not got websocket_to_posix_proxy to work properly yet, it is only sending data in one direction. I am testing different browsers because it may be a browser support problem.