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, 4 deletions

diff --git a/source/blender/blenkernel/BKE_pointcache.h b/source/blender/blenkernel/BKE_pointcache.h
index f31ae715539..cc60df1b2d6 100644
--- a/source/blender/blenkernel/BKE_pointcache.h
+++ b/source/blender/blenkernel/BKE_pointcache.h
@@ -227,7 +227,6 @@ typedef struct PTCacheEditPoint {
 } PTCacheEditPoint;
 
 typedef struct PTCacheUndo {
-	struct PTCacheUndo *next, *prev;
 	struct PTCacheEditPoint *points;
 
 	/* particles stuff */
@@ -240,12 +239,11 @@ typedef struct PTCacheUndo {
 	struct ListBase mem_cache;
 
 	int totpoint;
-	char name[64];
+
+	size_t undo_size;
 } PTCacheUndo;
 
 typedef struct PTCacheEdit {
-	ListBase undo;
-	struct PTCacheUndo *curundo;
 	PTCacheEditPoint *points;
 
 	struct PTCacheID pid;