Various small fixes (#427)

Various small fixes (#427)

* fix playback reporting on qobuz

* fix playlist create

* fix browse feature check

* add additional event type for finished background job

* small change to item linking logic

* avoid db duplicates with a simple lock

* guard search not supported by provider

* attach full album to albumtracks

* add db delete func

* add (back) events when media items update

* speedup add/remove to/from library

* update playlist when tracks added/removed

* fix playlists create/edit

* change playlist item removals to positions

* fix for album tracks listings

* prefer album image

* apply recursive delete

* fix browse feature