Forbid copying and assignment in layout classes.

Specifically in:
 * BAbstractLayout
 * BAbstractLayoutItem
 * BGridLayout
 * BGridView
 * BGroupLayout
 * BGroupView
 * BLayout
 * BSplitView
 * BTwoDimensionalLayout

headers/os/interface/GroupView.h

@@ -25,6 +25,12 @@ public:
 			BGroupLayout*		GroupLayout() const;
 
 	static	BArchivable*		Instantiate(BMessage* from);
+
+private:
+
+	// forbidden methods
+								BGroupView(const BGroupView&);
+			void				operator =(const BGroupView&);
 };