began admin section
modified admin/gallery.php: included hidden items and skipped gallery landing display
modified sidebar to include 'hidden'
modified slide.php: treats empty query string as new item; displays add form does no retrieval
modified gallery.php: added 'add new item' link to top of every gallery.php response
Added 'set theme' in admin's nav.php
added empty files with names referenced in slide.php and nav.php