title: How to convert HTML to Markdown while retaining non-markdown HTML tags?
body: <p>I'd like to be able to take an existing HTML snippet and convert it to markdown.
  I've tried pandoc for this purpose:</p>
  
  <pre><code>pandoc test.html -o test.md
  </code></pre>
  
  <p>where test.html looked like this:</p>
  
  <pre><code>Hello
  
  &lt;!-- more --&gt;
  
  and some more text
  
  &lt;h2&gt;some heading&lt;/h2&gt;       
  </code></pre>
  
  <p>The result was this:</p>
  
  <pre><code>Hello and some more text
  
  some heading
  ------------
  </code></pre>
  
  <p>Thus, it not only converts tags that have a direct meaning in markdown. It also removes tags that I would like to retain as HTML (e.g., HTML comments,  <code>iframe</code> tags, and so on).</p>
  
  <ul>
  <li>How can I convert HTML to markdown in a way that any tags that don't have an equivalent in markdown are retained as raw HTML?</li>
  <li>More generally how can I have control over how the HTML to markdown conversion is done?</li>
  </ul>
  
  <p>In particular, I'd be interested in command-line program options. For example, perhaps there are options that can be supplied to pandoc.</p>