[gnome-music] (7 commits) Non-fast-forward update to branch wip/mschraal/coremodel-use-flattened-main-models

[Marinus Schraal <mschraal src gnome org>]

The branch 'wip/mschraal/coremodel-use-flattened-main-models' was changed in a way that was not a 
fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  96ed5c1... coremodel: Flatten the core models
  b8f98fc... grltrackerwrapper: Do not declare coremodel var classwide

Commits added to the branch:

  e7a37b4... coredisc: Add callback error check (*)
  c2b5a1c... grltrackerwrapper: Remove unneeded arguments (*)
  29c5bd1... songwidget: Define song_number property (*)
  f195268... songwidget: Bind coresong properties (*)
  929e6ba... Update Kazakh translation (*)
  687fac8... coremodel: Flatten the core models
  980d5ae... grltrackerwrapper: Do not declare coremodel var classwide

(*) This commit already existed in another branch; no separate mail sent