WIP: XMPP stuff

Idea: develop an XMPP server component that implements PubSub and Libertree-specific extensions.

           .-------------.        .-----------------------.
XMPP <===  | XMPP Server |        |       Libertree       |
           |             | <----> |    server component   | <----> DB
           | elephly.net |        | libertree.elephly.net |         |
           |_____________|        |_______________________|         |
                                                                    |
                                                                 Frontend

Libertree server components address Libertree messages to other server components. The XMPP server automatically routes Libertree messages to the server component where they are processed. (More in XEP-0114.)

Goals

• reuse XMPP libraries that implement relevant XEPs
• offload message delivery, concurrency, infrastructure, etc. to XMPP server developers
• simplify deployment for those who already have an XMPP server

Relevant XEPs

• PubSub: XEP 0060
• TODO