GPencil: Refactor Append operators

Now the operators work like other areas of Blender using the list of selected objects.

Also, the name has been changed to:

```Layers:
- Copy Layer to Selected
- Copy All Layers to Selected

Materials:
- Copy Material to Selected
- Copy All Materials to Selected```

Reviewed By: mendio, pablovazquez, pepeland

Differential Revision: https://developer.blender.org/D11216

1 files changed, 4 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_gpencil.h b/source/blender/blenkernel/BKE_gpencil.h
index 4b4886e8bf3..bb145580928 100644
--- a/source/blender/blenkernel/BKE_gpencil.h
+++ b/source/blender/blenkernel/BKE_gpencil.h
@@ -108,7 +108,10 @@ void BKE_gpencil_stroke_select_index_reset(struct bGPDstroke *gps);
 
 struct bGPDframe *BKE_gpencil_frame_addnew(struct bGPDlayer *gpl, int cframe);
 struct bGPDframe *BKE_gpencil_frame_addcopy(struct bGPDlayer *gpl, int cframe);
-struct bGPDlayer *BKE_gpencil_layer_addnew(struct bGPdata *gpd, const char *name, bool setactive);
+struct bGPDlayer *BKE_gpencil_layer_addnew(struct bGPdata *gpd,
+                                           const char *name,
+                                           const bool setactive,
+                                           const bool add_to_header);
 struct bGPdata *BKE_gpencil_data_addnew(struct Main *bmain, const char name[]);
 
 struct bGPDframe *BKE_gpencil_frame_duplicate(const struct bGPDframe *gpf_src,