Three functionalities in one commit, but there's overlap so I can't

separate it...

1) Curve/Surface editmode undo
Uses same syntax as mesh undo, so simple to integrate. Edit-curve data is
also quite simpler, so no need for any hack at all.
It re-uses the undo system from next point, which is nice short & clean
local code

2) Framework for global undo
The undo calls themselves are commented out. In a next commit I want to
enable it for a couple of main features, for further feedback.
The speed goes surprisingly well, especially with this new version that
'pushes' undo after a command, ensuring interactivity isnt frustrated

3) framework for texture based icons in Blender
Not activated code, but tested here. Part of 2.3 UI project.

btw: Johnny Matthews will assist in (and complete) the undo project

source/blender/src/buttons_editing.c

@@ -647,7 +647,7 @@ static void editing_panel_mesh_type(Object *ob, Mesh *me)
 	if( uiNewPanel(curarea, block, "Mesh", "Editing", 320, 0, 318, 204)==0) return;
 
 	uiBlockBeginAlign(block);
-	uiDefButS(block, TOG|BIT|5, REDRAWVIEW3D, "Auto Smooth",10,180,154,19, &me->flag, 0, 0, 0, 0, "Treats all faces with angles less than Degr: as 'smooth' during render");
+	uiDefButS(block, TOG|BIT|5, REDRAWVIEW3D, "Auto Smooth",10,180,154,19, &me->flag, 0, 0, 0, 0, "Treats all set-smoothed faces with angles less than Degr: as 'smooth' during render");
 	uiDefButS(block, NUM, B_DIFF, "Degr:",				10,160,154,19, &me->smoothresh, 1, 80, 0, 0, "Defines maximum angle between face normals that 'Auto Smooth' will operate on");
 
 	uiBlockBeginAlign(block);