Chat Federation (and a lot more) WIP:

Note: websocket s2s is not working yet, still WIP.

New Features

* Chat Federation:
  * You can now connect to a remote chat with your local account.
  * This remote connection is done using a custom implementation of [XEP-0468: WebSocket S2S](https://xmpp.org/extensions/xep-0468.html), using some specific discovering method (so that it will work without any DNS configuration).

Minor changes and fixes

* Possibility to debug Prosody in development environments.
* Using process.spawn instead of process.exec to launch Prosody (safer, and more optimal).
* Prosody AppImage: fix path mapping: we only map necessary /etc/ subdir, so that the AppImage can access to /etc/resolv.conf, /etc/hosts, ...
* Prosody AppImage: hidden debug mode to disable lua-unbound, that seems broken in some docker dev environments.

prosody/appimage_x86_64.yml

@@ -58,7 +58,12 @@ AppDir:
     # Note: this assume that peertube-plugin-livechat is not in a subdir of one of following mappings.
     #       This seems a reasonable assumption.
     path_mappings:
-      - /etc/:$APPDIR/etc/
+      # Dont map entire /etc/ (or dns resolution will not work properly)
+      - /etc/init.d/:$APPDIR/etc/init.d/
+      - /etc/ld.so.conf.d/:$APPDIR/etc/ld.so.conf.d/
+      - /etc/logrotate.d/:$APPDIR/etc/logrotate.d/
+      - /etc/prosody/:$APPDIR/etc/prosody/
+      - /etc/ssl/:$APPDIR/etc/ssl/
       - /lib/:$APPDIR/lib/
       - /lib64/:$APPDIR/lib64/
       - /runtime/:$APPDIR/runtime/