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.

serverConnection is the global value in galene.js.

Thanks to Martin Pépin.

The authorisation server can now reply with 204 (no content)
in order to request that the client should continue with password
authentication.

Split into the protocol (in protocol.js) and the user interface
(in galene.js).  Make the state automaton explicit, and improve
error-handling.  The new protocol is incompatible with the old one.

Thanks to lamhai1401.

We used to avoid re-reading descriptions when joining a group,
but we used to re-read them when updating the list of groups.

We already depend on jwt, which requires go 1.16.