rm unfinished undo/redo engine (#757)

This resolves #757 (closed).

GUI/View/SampleDesigner/SampleEditorController.h

@@ -19,11 +19,11 @@
 #include "GUI/Model/Sample/ItemWithParticlesCatalog.h"
 #include <QUndoStack>
 
-class ISelectionContainerForm;
-class ISelectionProperty;
 class CompoundItem;
 class CoreAndShellForm;
 class DoubleProperty;
+class ISelectionContainerForm;
+class ISelectionProperty;
 class InterferenceForm;
 class InterferenceItem;
 class Item3D;
@@ -34,10 +34,10 @@ class LayerForm;
 class LayerItem;
 class MaterialModel;
 class MesocrystalForm;
-class SampleForm;
-class SampleItem;
 class ParticleLayoutItem;
 class ProjectDocument;
+class SampleForm;
+class SampleItem;
 class SelectionContainerForm;
 
 //! Class to modify a sample from the layer oriented sample editor.