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, 2 insertions, 0 deletions

diff --git a/source/blender/blenkernel/CMakeLists.txt b/source/blender/blenkernel/CMakeLists.txt
index 25954f277b8..d789671ab24 100644
--- a/source/blender/blenkernel/CMakeLists.txt
+++ b/source/blender/blenkernel/CMakeLists.txt
@@ -188,6 +188,7 @@ set(SRC
 	intern/tracking_solver.c
 	intern/tracking_stabilize.c
 	intern/tracking_util.c
+	intern/undo_system.c
 	intern/unit.c
 	intern/world.c
 	intern/writeavi.c
@@ -296,6 +297,7 @@ set(SRC
 	BKE_text.h
 	BKE_texture.h
 	BKE_tracking.h
+	BKE_undo_system.h
 	BKE_unit.h
 	BKE_world.h
 	BKE_writeavi.h