[gimp] (14 commits) Non-fast-forward update to branch wip/passthrough

[N/A <ell src gnome org>]

The branch 'wip/passthrough' 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:

  bd1101c... ^^^ wip/passthrough ^^^
  48bd25d... app: add pass-through layer mode
  ad63454... app: add GimpDrawable::get_source_node() vfunc
  a183f9b... app: connect layer backdrop to source node's input
  1f29b48... app: implement pass-through mode in GimpGroupLayer
  92ba1c1... app: add gimp_projectable_{begin,end}_render()
  60cd584... app: add GimpTileHandlerProjectable
  b5d09a5... app: use {begin,end}_render() and GimpTileHandlerProjectabl
  d9d6202... app: implement {begin,end}_render() for GimpGroupLayer
  80a1c16... app: move bottom-layer special casing to GimpOperationLayer

Commits added to the branch:

  b0d2d4f... app: indentation fix. (*)
  3f7b135... app: fix memory leak in gimp_image_merge_layers() (*)
  3ae9c12... app: fix more leaks in gimp_image_merge_layers() (*)
  56249ed... ^^^ wip/passthrough ^^^
  7739e17... app: add pass-through layer mode
  dff05d9... app: add GimpDrawable::get_source_node() vfunc
  407c7a4... app: connect layer backdrop to source node's input
  50546fb... app: implement pass-through mode in GimpGroupLayer
  e6d5472... app: add gimp_projectable_{begin,end}_render()
  4fe762b... app: add GimpTileHandlerProjectable
  c8d7f91... app: use {begin,end}_render() and GimpTileHandlerProjectabl
  6fc53af... app: implement {begin,end}_render() for GimpGroupLayer
  e8da1b2... app: move bottom-layer special casing to GimpOperationLayer
  dba0d5c... app: adapt gimp_image_merge_layers() to handle pass-through

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