Replace XMPP library in Moodle to something supported and move from core to message/output/jabber

just had a chat with Nathan Fritz, I guess it's self-explanatory:

(15:52:32) Marina: Hello Nathan, my name is Marina Glancy and I work for Moodle HQ
(15:53:24) Marina: We are preparing Moodle for PHP7 at the moment and found an issue in XMPP
(15:53:32) Marina: https://tracker.moodle.org/browse/MDL-52335 for more details
(15:53:39) Fritzy: okay...
(15:54:00) Marina: do you maintain source code in svn only? no github?
(15:54:09) Fritzy: I haven't supported that library in a long time – since before I was on github.
(15:54:33) Fritzy: https://github.com/cweiske/xmpphp is the most recent (he was going to start maintaining it)
(15:54:45) Marina: that's a shame, should we just patch it in our product then?
(15:55:08) Fritzy: Yup. If your developers want to take it over, that'd be great too.
(15:55:16) Fritzy: Feel free to publish it on Github.
(15:55:28) Fritzy: I can give you an MIT version
(15:55:32) Marina: last commit 5 years ago
(15:55:46) Fritzy: Yup, pretty old. There are better maintained XMPP libraries for PHP
(15:56:01) Fritzy: https://xmpp.org/xmpp-software/libraries/
(15:56:35) Fritzy: https://github.com/jaxl/JAXL
(15:57:34) Fritzy: In any case, if you like I can make a fork in a more permissive license. But yeah, I'd recomend moving to something more maintained