Undo: unified undo system w/ linear history

- Use a single undo history for all operations.
- UndoType's are registered and poll the context to check if they
  should be used when performing an undo push.
- Mode switching is used to ensure the state is correct before
  undo data is restored.
- Some undo types accumulate changes (image & text editing)
  others store the state multiple times (with de-duplication).
  This is supported by checking UndoStack.mode `ACCUMULATE` / `STORE`.
- Each undo step stores ID datablocks they use with utilities to help
  manage restoring correct ID's.
  Needed since global undo is now mixed with other modes undo.
- Currently performs each undo step when going up/down history
  Previously this wasn't done, making history fail in some cases.
  This can be optimized to skip some combinations of undo steps.

grease-pencil is an exception which has not been updated
since it integrates undo into the draw-session.

See D3113

1 files changed, 1 insertions, 0 deletions

diff --git a/source/blender/editors/include/ED_object.h b/source/blender/editors/include/ED_object.h
index 5b2fdf29dd5..7faf975ea91 100644
--- a/source/blender/editors/include/ED_object.h
+++ b/source/blender/editors/include/ED_object.h
@@ -196,6 +196,7 @@ void ED_object_constraint_dependency_tag_update(struct Main *bmain, struct Objec
 bool ED_object_mode_compat_test(const struct Object *ob, eObjectMode mode);
 bool ED_object_mode_compat_set(struct bContext *C, struct Object *ob, eObjectMode mode, struct ReportList *reports);
 void ED_object_mode_toggle(struct bContext *C, eObjectMode mode);
+void ED_object_mode_set(struct bContext *C, eObjectMode mode);
 
 /* object_modifier.c */
 enum {