[gnome-music] (19 commits) Non-fast-forward update to branch wip/mschraal/core-thumb-property

[Jean Felder <jfelder src gnome org>]

The branch 'wip/mschraal/core-thumb-property' 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:

  a17e2a3... coreartist: Rework retrieval
  29cdee0... artistart: Split out retrieval and cache storage
  6891a14... artcache: Unify DefaultIcon and _make_icon_frame
  ea63e74... artistartstack: Disconnect cache callback
  cb6d65e... artistartstack: Remove DefaultIcon use
  f7eff1e... artistartstack: Remove unused variable
  5cf7a6e... artstack: Renamed from ArtistArtStack
  7f7b21b... artstack: Add default size setter
  a985d7f... corealbum: Add thumbnail property
  118cf08... Rename StoreArtist to StoreArt
  361e5a9... Restore embedded art support
  f40e67b... artstack: Disconnect notification on coreobject change
  0826d31... coresong: Add thumbnail property
  3947b43... mpris: Use CoreSong thumbnail property
  33a7b46... utils: Add ArtSize enum
  ef567e9... Remove coverstack.py and albumartcache.py
  951b6d8... grltrackerwrapper: Clarify function name
  3d14bc9... grltrackerwrapper: Consolidate art queries

Commits added to the branch:

  d7b04d6... Update Chinese (China) translation (*)
  cb5766f... coreartist: Rework retrieval
  846053c... artistart: Split out retrieval and cache storage
  dcb1077... artcache: Unify DefaultIcon and _make_icon_frame
  c03e51f... artistartstack: Disconnect cache callback
  f5a4f55... artistartstack: Remove DefaultIcon use
  69759bd... artistartstack: Remove unused variable
  16d1471... artstack: Renamed from ArtistArtStack
  0a7ed43... artstack: Add default size setter
  ad41ee5... corealbum: Add thumbnail property
  bfb5ecb... Rename StoreArtist to StoreArt
  ddf5b6b... Restore embedded art support
  3609a06... artstack: Disconnect notification on coreobject change
  6e82e6a... coresong: Add thumbnail property
  8aec1da... mpris: Use CoreSong thumbnail property
  531e6ad... utils: Add ArtSize enum
  fb59496... Remove coverstack.py and albumartcache.py
  4a78f90... grltrackerwrapper: Clarify function name
  1e98f73... grltrackerwrapper: Consolidate art queries

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