GPencil: Changes in Fill and new 3D Cursor View Plane

This commit groups several options that were tested in grease pencil branch:

- Changes to fill algorithms and improves, specially in small areas and stroke corners.
  New options has been added in order to define how the fill is working and internally there are optimizations in detect the small areas in the extremes.

  Kudos to @charlie for coding this fill improvements.

- New 3D cursor view plane option.

  Now it's possible to lock the drawing plane to the 3D cursor and use the 3D cursor orientation. This allows more flexibility when you are drawing and reduce the need to create geometry to draw over surfaces.

- Canvas Grid now can be locked to 3D cursor.
- New option to reproject stroke using 3D cursor.
- Small tweaks and fixes.

Changes reviewed by @pepeland and @mendio

1 files changed, 2 insertions, 0 deletions

diff --git a/source/blender/editors/include/ED_gpencil.h b/source/blender/editors/include/ED_gpencil.h
index e331032bd6e..fdbb8556891 100644
--- a/source/blender/editors/include/ED_gpencil.h
+++ b/source/blender/editors/include/ED_gpencil.h
@@ -225,9 +225,11 @@ void ED_gpencil_add_defaults(struct bContext *C, struct Object *ob);
 void ED_gpencil_setup_modes(struct bContext *C, struct bGPdata *gpd, int newmode);
 
 void ED_gp_project_stroke_to_plane(
+		const struct Scene *scene,
         const struct Object *ob, const struct RegionView3D *rv3d,
         struct bGPDstroke *gps, const float origin[3], const int axis);
 void ED_gp_project_point_to_plane(
+		const struct Scene *scene,
         const struct Object *ob, const struct RegionView3D *rv3d,
         const float origin[3], const int axis, struct bGPDspoint *pt);
 void ED_gp_get_drawing_reference(