Use first heading even if there is a line of code first

Proposes a fix for issue #265.

It works in so far that you don't see two headings if your file starts with something like

    <?php
    // # My Heading

However, `My Heading` will not be displayed at the top of the file (and uncommented `<?php`) will appear first. To fix that, you would somehow have to remove the HTML of the first heading from its own section. I wasn't really sure what the cleanest way to do that would be, so I left it as is.