Implement best size calculation for report mode wxListCtrl.

Use the column labels to determine the minimal width required by the control
to show them all in full.

Also declare all image list and column-related wxListCtrl methods in
wxListCtrlBase now as we need some of them in DoGetBestClientSize()
implementation.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70282 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/listctrl.h

@@ -16,7 +16,6 @@
 #include "wx/dynarray.h"
 #include "wx/vector.h"
 
-class WXDLLIMPEXP_FWD_CORE wxImageList;
 class wxMSWListItemData;
 
 // define this symbol to indicate the availability of SetColumnsOrder() and
@@ -320,14 +319,6 @@ public:
     // Insert an image/string item
     long InsertItem(long index, const wxString& label, int imageIndex);
 
-    // For list view mode (only), inserts a column.
-    long InsertColumn(long col, const wxListItem& info);
-
-    long InsertColumn(long col,
-                      const wxString& heading,
-                      int format = wxLIST_FORMAT_LEFT,
-                      int width = -1);
-
     // set the number of items in a virtual list control
     void SetItemCount(long count);
 
@@ -393,6 +384,9 @@ protected:
     // common part of all ctors
     void Init();
 
+    // Implement base class pure virtual methods.
+    long DoInsertColumn(long col, const wxListItem& info);
+
     // free memory taken by all internal data
     void FreeAllInternalData();