title: Doxygen: include custom latex command
body: <p>I want to generate some images using the <code>tikz-uml</code> package These images should be shown also in HTML format, like formulas. In a normal latex document in order to draw these images I write</p>
  
  <pre><code>\documentclass[a4paper,10pt,openright,twoside,final]{memoir}
  ...
  \usepackage{tikz}
  \usepackage{tikz-uml}
  \usetikzlibrary{positioning}
  
  
  \begin{document}
   \begin{tikzpicture}
  \begin{umlpackage}[x=0,y=0,fill=red!10]{package}
  ...
  \end{umlpackage}
  \end{tikzpicture}
  \end{document}
  </code></pre>
  
  <p>In particular I need to call <code>usetikzlibrary{positioning}</code> after package declaration.</p>
  
  <p>In the doxyfile I can put <code>\usepackage{tikz-uml}</code> with <code>EXTRA_PACKAGES</code> variable, that's works also when using LaTeX in html, but I don't know how put into the doxyfile the command <code>\usetikzlibrary{positioning}</code> that I need in order to define my images. How can I tell doxygen to add this line?</p>