Forbid copying and assignment in layout classes.

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

headers/os/interface/GridView.h

@@ -24,6 +24,12 @@ public:
 			BGridLayout*		GridLayout() const;
 
 	static	BArchivable*		Instantiate(BMessage* from);
+
+private:
+
+	// forbidden methods
+								BGridView(const BGridView&);
+			void				operator =(const BGridView&);
 };