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, 0 insertions, 1 deletions

diff --git a/source/blender/editors/physics/physics_intern.h b/source/blender/editors/physics/physics_intern.h
index cb281936634..f3f3697caaa 100644
--- a/source/blender/editors/physics/physics_intern.h
+++ b/source/blender/editors/physics/physics_intern.h
@@ -68,7 +68,6 @@ void PARTICLE_OT_edited_clear(struct wmOperatorType *ot);
 
 void PARTICLE_OT_unify_length(struct wmOperatorType *ot);
 
-void PTCacheUndo_clear(struct PTCacheEdit *edit);
 void PE_create_particle_edit(struct Scene *scene, struct Object *ob, struct PointCache *cache, struct ParticleSystem *psys);
 void recalc_lengths(struct PTCacheEdit *edit);
 void recalc_emitter_field(struct Object *ob, struct ParticleSystem *psys);