Workaround for archive navigation display

On the archive pages, the navigation (previous / later posts) is included in the <ul></ul> block surrounding the <li> entries.

I *think* that is due to this code in ´archive.php´:

   <ul>
   <?php get_template_part( 'loop', 'archive' ); ?>
   </ul>

That will generate the navigation "in between", it seems.

As I've no time to fix the PHP code, I just added some whitespace - and a separator line - via CSS. It's a kludge, but it works for now.
Merge pull request #118 from th-h/patch-3

Workaround for archive navigation display