Optional header.php and footer.php
Fix link to files with downloads.
Fix typo.
Revert "Fix link to files with downloads."

This reverts commit 65bfd83148ee0f91671a9a8ff507401d0302165c.
Re-struture logic of determining urlpath for normal items.
Fix typos.
Don't urlencode directory separators for direct (file) links.
Add feature to link to, rather than browse, directories with their own index.
Use archive icon for archive files instead of briefcase.