We're already doing it in the receiver loop.

Doing that at the sample level suffers from too much delay
due to buffering in the samplebuilder.

This fixes an issue with out-of-order packet's start flag not
being correctly set in all cases.

If the stream was very short, we may not have created
a writer yet.  Write out packets even in that case.

Apparently the field has a different name than the HTML attribute.

Chromium 91 and later uses "AV1" instead of "AV1X".  Simulcast is
still broken.

Show the "hand-paper" symbol instead of the "circle" symbol while a
user is raising their hand.

(*webClient).action may be called with the group mutex taken,
and therefore cannot take the client mutex.

This prevents simulcast from being switched on when we enable
recording.

We now request a keyframe if we lose too many packets.

This version fixes issues with out-of-order packets.

This avoids a crash when a single frame was too large for the
samplebuilder.

Fix small typo

This makes for better error messages.