addMapping assumes the piddelta is constant, so it doesn't need
the pid.

When using an identity packetmap, we used to update the next seqno
even when packets were not increasing.  Not a big deal, we'd still
recover at the next sequential packet.

Don't disconnect the client for some more errors.

This does not yet support the new 'need-username' error.

The code turned out not to port to FreeBSD.  Disable the check,
and assume that FreeBSD admins read the docs.

Thanks to Amatis-51.

Pion is unfortunately breaking Go 1.16.

It was introduced in Go 1.19.

The strategy of computing the base URL from the request doesn't
necessarily work if we're behind a reverse proxy.  proxyURL
can be set in cases where our guess is incorrect.

Thanks to Dianne Skoll.

We were computing the scheme incorrectly, which caused us
to compute the wrong websocket URL when -insecure is set.
Thanks to Fabien de Montgolfier.

When we fixed the handling of autolocked groups, we introduced
a bug where we spuriously notify clients even when the description
didn't change.

When we moved the chat history to the client goroutine back in 0.6,
we started sending the history whenever the group configuration changed.
Only send it when first joining the group.  Thanks to Rémi Nollet.

We used to autolock groups when the last user left, but not
when creating a group that was not in memory yet.  Ensure that
groups are autolocked in all cases.

Thanks to Michael Ströder.

This just removes a minor optimisation.

This avoids issues with redirects.

Now that we have an indicator in the users list, it is reasonable
to hide audio-ony peers by default.

It's redundant, the data is already in the stream.

This was broken when we moved GetPermission to Group.
Thanks to kiufta.

Chathistory messages were formatted incorrectly.
We were also not formatting correctly messages from
anonymous users.

We used to send the chat history from the reader goroutine,
which would cause them to race with the join message.

The handshake message now contains a list of supported protocol
versions.  Version mismatch is currently a warning, but it will be a
hard error in the future.

This avoids hard-wiring URLs in the client.