RNA: Cleanup PointerRNA struct

The old layout of `PointerRNA` was confusing for historic reasons:
```
typedef struct PointerRNA {
  struct {
    void *data;
  } id;

  struct StructRNA *type;
  void *data;
} PointerRNA;
```

This patch updates it to:
```
typedef struct PointerRNA {
  struct ID *owner_id;
  struct StructRNA *type;
  void *data;
} PointerRNA;
```

Throughout the code base `id.data` was replaced with `owner_id`.
Furthermore, many explicit pointer type casts were added which
were implicit before. Some type casts to `ID *` were removed.

Reviewers: brecht, campbellbarton

Differential Revision: https://developer.blender.org/D5558

1 files changed, 2 insertions, 2 deletions

diff --git a/source/blender/editors/interface/interface_layout.c b/source/blender/editors/interface/interface_layout.c
index e9b9411e1bd..85c7af26b72 100644
--- a/source/blender/editors/interface/interface_layout.c
+++ b/source/blender/editors/interface/interface_layout.c
@@ -1873,7 +1873,7 @@ void uiItemFullR(uiLayout *layout,
     uiBut *but;
   } ui_decorate = {
       .use_prop_decorate = (((layout->item.flag & UI_ITEM_PROP_DECORATE) != 0) &&
-                            (use_prop_sep && ptr->id.data && id_can_have_animdata(ptr->id.data))),
+                            (use_prop_sep && ptr->owner_id && id_can_have_animdata(ptr->owner_id))),
   };
 #endif /* UI_PROP_DECORATE */
 
@@ -2946,7 +2946,7 @@ void uiItemLDrag(uiLayout *layout, PointerRNA *ptr, const char *name, int icon)
 
   if (ptr && ptr->type) {
     if (RNA_struct_is_ID(ptr->type)) {
-      UI_but_drag_set_id(but, ptr->id.data);
+      UI_but_drag_set_id(but, ptr->owner_id);
     }
   }
 }