title: Doxygen - any way to get a module hierarchy?
body: <p>It seems that even if I specify my groups as follows:</p>
  
  <pre><code>@defgroup MainGroup
  @brief ...
  
  @defgroup SubGroup1
  @brief ...
  @ingroup MainGroup
  
  @defgroup SubGroup2
  @brief ...
  @ingroup SubGroup1
  </code></pre>
  
  <p>The hierarchy in the "Modules" chapter isn't being respected by doxygen in the latex output (rendered as PDF): all the groups are treated as modules in <strong>the same</strong> level:</p>
  
  <pre><code>Modules
    MainGroup
    SubGroup1
    SubGroup2
  </code></pre>
  
  <p>Any way to solve this?</p>