Merge branch 'listctrl-itemrect'

Improve wxListCtrl::GetSubItemRect() and add a unit test for it.

See https://github.com/wxWidgets/wxWidgets/pull/1511

include/wx/generic/private/listctrl.h

@@ -649,7 +649,8 @@ public:
     {
         return GetSubItemRect(item, wxLIST_GETSUBITEMRECT_WHOLEITEM, rect);
     }
-    bool GetSubItemRect( long item, long subItem, wxRect& rect ) const;
+    bool GetSubItemRect( long item, long subItem, wxRect& rect,
+                         int code = wxLIST_RECT_BOUNDS ) const;
     wxRect GetViewRect() const;
     bool GetItemPosition( long item, wxPoint& pos ) const;
     int GetSelectedItemCount() const;