HLS: Include EXT-X-VERSION and EXT-X-ALLOW-CACHE tags in playlist.
WebFrontend: Reduce bitrates in line with a different Apple doc, not sure which of the two is authoritative but might as well go with the one which allows smoother streaming.
Improve the logic by which we decide which H.264 profile to use. We should endevour to use the lowest possible profile and baseline allowed by the chosen resolution and bitrate to support the widest variety of playback devices.
WebFrontend: Disable the 720p video option for now, you need decent hardware to transcode to 720p in realtime. Until we can figure out a way to disable it selectively on systems that can't handle it, it's better not to even offer it as a choice.