Hide the rename and delete columns in the generic popup

The popup is meant for browsing and selection, not editing and library
management. Renaming and deleting submits forms and confuses the
parent page in which the popup dialog is opened.
Handle links correctly inside the generic popup (jquery dialog)

Specifically:

- If target="_blank", let it be handled normally (new window) instead
  of opening it inside the dialog. Fixes image links.

- If href is a just a query string, append it to the current url that
  is open inside the popup instead of the parent page url. Fixes
  filters and sort links.
Hide the upload and new folder buttons in the generic popup

The buttons require scripts that are not available in the popup,
because the jquery .load() function strips out <script> tags.
Apply popup layout tweaks to all popup types.
Version bump to 0.2.17
Restore styles for jquery popups.
Version bump to 0.2.18