This adds:

• some escaping
• removes the PHP4 action hooks, we don't need to do array( &$this... we can just do array( $this
• Fixes a PHP warning on the tools page for an undefined offset
• Fixes the way that the scripts and styles are enqueued so that they're only enqueued on the correct hook
• Use the parameters from the hook used in the previous fix to conditionally load the styles rather than looking at the $_SERVER global