This will convert the tree into a format needed for some new features in 1.3. Your <1.3 tree will still work without converting but some new features like preorder sorting won't work as expected.
Usage: - Create a new node table (tb_nodes2) from the current node table (tb_nodes1) (only copy the structure). - Create a nested set instance of the 'old' set (NeSe1) and one of the new set (NeSe2) - Now you have 2 identical objects where only node_table differs - Call DB_NestedSet::convertTreeModel(&$orig, &$copy); - After that you have a cleaned up copy of tb_nodes1 inside tb_nodes2