POC: Add HLS streaming

[qstokkink]

Now that we have a proper web front-end, we can update to newer standards for streaming that should work out-of-the-box in a modern web browser.

In particular, I think it would be nice to support HLS.

Whether this is better or worse than our current streaming implementation remains to be seen. However, I think it's worth a short to attempt a quick proof of concept.

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My initial idea for the POC is to spawn an instance of ffmpeg to forward a video file into HLS format (something along these lines). On the web/javascript side, this would be no different from playing a HLS stream from any other source.

[qstokkink]

After taking some time to reflect on this, I think we should close this issue: "if it ain't broke [...]".