Mask Editor: Add toggle for mask spline drawing

Adds an overlay option to show/hide the spline points & lines of masks in the Mask Editor.

It also moves the "smooth" option up (its position left of the selection dropdown was missleading).

{F11847272}

This emerged from a discussion in https://developer.blender.org/D12776

Differential Revision: https://developer.blender.org/D13314

source/blender/blenloader/intern/versioning_300.c

@@ -30,6 +30,7 @@
 #include "DNA_gpencil_modifier_types.h"
 #include "DNA_lineart_types.h"
 #include "DNA_listBase.h"
+#include "DNA_mask_types.h"
 #include "DNA_material_types.h"
 #include "DNA_mesh_types.h"
 #include "DNA_modifier_types.h"
@@ -3096,6 +3097,21 @@ void blo_do_versions_300(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
   }
 
+  if (!MAIN_VERSION_ATLEAST(bmain, 303, 3)) {
+    LISTBASE_FOREACH (bScreen *, screen, &bmain->screens) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
+          if (sl->spacetype == SPACE_CLIP) {
+            ((SpaceClip *)sl)->mask_info.draw_flag |= MASK_DRAWFLAG_SPLINE;
+          }
+          else if (sl->spacetype == SPACE_IMAGE) {
+            ((SpaceImage *)sl)->mask_info.draw_flag |= MASK_DRAWFLAG_SPLINE;
+          }
+        }
+      }
+    }
+  }
+
   /**
    * Versioning code until next subversion bump goes here.
    *