GitLab

Also:
- Add get_conversation_messages() to PluginAPI
- Make plugins_autoload colon-separated instead of space-separated
    (for consistency)
- Replace a JID() with a safeJID() in the uptime plugin

And fix some imprecisions/mistakes in the help.

Do not traceback when:
    - The song has no album
    - the song has no title
    - the song has no artist
    - the playlist is empty
    - mpd is not playing

do not catch errors, actually, since there’s a bug in the mpd lib with python3 that makes it impossible to catch.