OBS Add Simulcast Support

This is something I have been working on for years and am sssooo excited to see merged. This starts a new generation of broadcasting (I hope)

* Cheaper servers. More competition and I want to see people running their own servers.

* Better video quality. Encoding from source is going to be better then transcoding.

* No more bad servers. Send video to your audience and server isn't able to do modification/surveillance with E2E Encryption via WebRTC.

* Better Latency. No more time lost transcoding. I love low latency streaming where people are connected to community. Not just blasting one-way video.

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Please please test it out! I want to catch any bugs/make improvements before branch cut.