Preserve header and label editing mode while recreating the grid

For some operations when grid needs to be recreated currently selected options to show the header and to enable label editing are being ignored and it can be seen a discrepancy between the options selected (and shown) in the menu and the mode of just created wxPropertyGrid. To avoid this inconsistency respective flags can be stored and used to enable/disable features in just created grid.

samples/propgrid/propgrid.h

@@ -153,6 +153,8 @@ public:
     wxVariant       m_storedValues;
 
     wxString        m_savedState;
+    bool            m_hasHeader;
+    bool            m_labelEditingEnabled;
 
 
     void CreateGrid( int style, int extraStyle );