v0.5.6

• front-end optimizations (#614, #615 by @Biont)
• optimize number of DB queries when building collection.json (may help on #601)
• check validity of the passed user names in the occ command line tool (#602)
• support for --group option in all occ commands (#613 by @greku)
• remote playlist support on the Ampache API (#611)
• support for actions artist and album on the Ampache API (used at least by Power Ampache)
• support for Nextcloud 14
• fix controls pane layout on Nextcloud 13 and 14 (#617)