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.

This was already the case for FU NALUs, but not for simple NALUs.

This contains some important optimisations for CTR mode.

Thanks (and sorry) to Fabrice Rouillier.