Add wxListCtrl::Set{Normal,Small}Images()

These new functions allow to use wxBitmapBundle for the images in this
control instead of wxImageList.

Update the sample to use the new API.

include/wx/generic/listctrl.h

@@ -212,7 +212,7 @@ public:
 protected:
     // Implement base class pure virtual methods.
     long DoInsertColumn(long col, const wxListItem& info) wxOVERRIDE;
-    void DoSetImageList(wxImageList *imageList, int which) wxOVERRIDE;
+    void DoUpdateImages(int which) wxOVERRIDE;
 
     virtual wxSize DoGetBestClientSize() const wxOVERRIDE;