Menus with type="header" are not processed by site.jsl

Menu items in navigation.xml with type="header" are not processed by site.jsl, at least in the examples that I have looked at. I am attaching a patch (site.jsl.patch) that fixes the problem and one that illustrates it (failure.patch) by changing the "Getting Maven" menu in the maven-core navigation.xml to have "header" type. When this change is made, the menu disappears from the generated site. After the site.jsl patch is applied, header type menus are processed and appear at the top.