1. some minor compilation fixes in datetime.cppm

2. implemented wxTreeCtrl::Insert(size_t index)
3. draft of wxCalendarCtrl


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@5135 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/generic/treectrl.h

@@ -337,9 +337,9 @@ public:
                             int image = -1, int selectedImage = -1,
                             wxTreeItemData *data = NULL);
 
-        // insert a new item before a given one
+        // insert a new item before the one with the given index
     wxTreeItemId InsertItem(const wxTreeItemId& parent,
-                            size_t before,
+                            size_t index,
                             const wxString& text,
                             int image = -1, int selectedImage = -1,
                             wxTreeItemData *data = NULL);