Multi-level support of navigation
It would be convenient for some projects do enable multi-level support in the navbar, e.g.
<submenu label="Edition" label-en="Edition">
<submenu label="Nösselt" label-en="Nösselt">
<item label="-- Vorwort zur Edition" link="foreword.html?author=noesselt"/>
<item label="-- Edition" link="book.html?file=noesselt-1-front"/>
<item label="-- Registerübersicht" link="index-selection.html?author=noesselt"/>
</submenu>
</submenu>
Edited by Michelle Weidling