Drop object assets and associated objects at the cursor location

When dropping asset objects, place them under the mouse-cursor
along with any other objects they link in.

Ref D12935

Reviewed By: Severin

source/blender/editors/include/ED_object.h

@@ -122,6 +122,8 @@ void ED_object_xform_skip_child_container_item_ensure(struct XFormObjectSkipChil
                                                       struct Object *ob_parent_recurse,
                                                       int mode);
 
+void ED_object_xform_array_m4(struct Object **objects, uint objects_len, const float matrix[4][4]);
+
 /* object_ops.c */
 void ED_operatortypes_object(void);
 void ED_operatormacros_object(void);