added wxHeaderCtrl::ResetColumnsOrder() function; use it from wxGrid

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57337 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/headerctrl.h

@@ -268,6 +268,14 @@ public:
      */
     unsigned int GetColumnPos(unsigned int idx) const;
 
+    /**
+        Reset the columns order to the natural one.
+
+        After calling this function, the column with index @c idx appears at
+        position @c idx in the control.
+     */
+    void ResetColumnsOrder();
+
     /**
         Helper function to manipulate the array of column indices.