Major Description
Given the xdoc snippet
<source class="pretty">some source</source>
the generated html output is
<div class="source"><pre>some source</pre></div>
ie the class attribute gets replaced. I think the correct output should be
<div class="source"><pre class="pretty">some source</pre></div>
Another problem: take
<source id="pretty">some source</source>
This gets transformed into
<div class="source" id="pretty"><pre id="pretty">some source</pre></div>
which is not valid xhtml because of the duplicate id.