scan parser: If a scan would be shown to a user on !request, but is added after the request, show it to the user.

Signed-off-by: Martin Stone <martin@d7415.co.uk>
scans: Added option to show the URL of completed scans in the "delivered" message.

Signed-off-by: Martin Stone <martin@d7415.co.uk>
settings for #scans

Signed-off-by: Martin Stone <martin@d7415.co.uk>