On specific servers, document/markdown feature makes issues ( reported by Maxon )

How to reproduce:

( on specific server rules )

• Remove the default documents ( pdf, md )

Result:

• No images, no documents displayed
• Image can appear if the default documents exist ; and a fake folder '/' is also listed.
• Removing the markdown document manually in 'switch' list at the end of index.php solve the issue but remove the feature...

The version in unstable branch already list subdirectories, but when you click on it, it just change URL of the directory. Something smarter would be to display the content of the artwork of this folder in the page.