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/qt/listctrl.h

@@ -269,7 +269,7 @@ protected:
 
     // Implement base class pure virtual methods.
     virtual long DoInsertColumn(long col, const wxListItem& info) wxOVERRIDE;
-    void DoSetImageList(wxImageList *imageList, int which) wxOVERRIDE;
+    void DoUpdateImages(int which) wxOVERRIDE;
 
     bool              m_hasCheckBoxes;