Avoid bool argument in wxListMainWindow::RecalculatePositions()

Use 2 separate functions instead to make the code more clear, as passing
false for indicate the refresh shouldn't be done was quite confusing.

Also get rid of a separate RefreshAll() which was called only from
RecalculatePositions().

No real changes.

include/wx/generic/private/listctrl.h

@@ -695,10 +695,10 @@ public:
         { return m_small_image_list; }
 
     // set the scrollbars and update the positions of the items
-    void RecalculatePositions(bool noRefresh = false);
+    void RecalculatePositions();
 
-    // refresh the window and the header
-    void RefreshAll();
+    // do the same thing and also call Refresh()
+    void RecalculatePositionsAndRefresh();
 
     long GetNextItem( long item, int geometry, int state ) const;
     void DeleteItem( long index );