Redirect to URLs

[LegalizeAdulthood]

For online documents, urls should be given that redirect through the PHP application. The PHP application attempts to verify that the resource is located at the URL and then redirects the user to that URL.

For HTTP URLs, this implies doing a HEAD and then a redirect header. I'm not sure how this would work for FTP URLs, perhaps the redirect would be done without any attempt to verify.

For URLs where the HTTP HEAD request fails, log them in the database and mark the document as possibly offline.

For offline copies with mirrors, check mirror copies and redirect to those in rank order.

For copies previously marked offline, display the last check date in the details view and a warning that the copy may be unavailable.