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, 1 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_context.h b/source/blender/blenkernel/BKE_context.h
index 755a155653b..bfcfd753975 100644
--- a/source/blender/blenkernel/BKE_context.h
+++ b/source/blender/blenkernel/BKE_context.h
@@ -239,7 +239,7 @@ bool CTX_data_dir(const char *member);
 
 #define CTX_DATA_BEGIN_WITH_ID(C, Type, instance, member, Type_id, instance_id) \
   CTX_DATA_BEGIN (C, Type, instance, member) \
-    Type_id instance_id = ctx_link->ptr.id.data;
+    Type_id instance_id = (Type_id)ctx_link->ptr.owner_id;
 
 int ctx_data_list_count(const bContext *C, int (*func)(const bContext *, ListBase *));