Enhanced treemenu operator
==========================
Original author: Jonny Bergkvist

The treemenu operator in eZ Publish has been enhanced for 3.8.
It now has extra values for each menu entry and has two new parameters.

The new parameters are:

- indentation_level: int          - The indentation level for the menu entries.
                                    (see indent)
- language         : string|array - The languages to use when fetching the nodes,
                                    this overrides the default in the siteaccess.
                                    Use either a string, e.g. nor-NO, or an array
                                    of strings, e.g. array( 'nor-NO', 'eng-GB' ).
                                    The languages are prioritized according to
                                    the array.

The new values are:

- is_main_node: bool   - is set to true when the node is a main_node.
- has_children: bool   - is set to true when the node has children
- indent      : int    - the current indentation (see indentation_level) of the
                         menu entry, this saves you calculating the value each
                         time.
- data_map    : array  - The data_map from the node.
- class_name  : string - The name of the content class for the menu entry,
                         e.g. 'Folder'.