Overview: 

Text between <pre> and </pre> tags is pre-processes according to the Markdown format

Steps to Reproduce: 

1) Text describing a folder tree:
<pre>
 + MyFolder
   + File1
   + File2
</pre>

2) run Doxygen (with default Doxyfile)

Actual Results: 

Foo.txt:9: warning: found </pre> at different nesting level (8) than expected (2)
Foo.txt:10: warning: end of comment block while expecting command </pre>

Html output:
<p>Text describing a folder tree:</p>
<pre><ul>
<li>Folder<ul>
<li>File1</li>
<li>File2

</li>
</ul>
</li>
</ul>
</pre>


Expected Results: 

Pre-processing should be disable in <pre>..</pre> block

Html output:
<p>Text describing a folder tree:</p>
<pre> + Folder
   + File1
   + File2
</pre>