Log Message:
Update to 1.3: Contributed by Stefan Schumacher (stefan net-tex de) in
private mail, ok'd by lukem. Changes:

> Use the URL node and {head,tail}URL edge-attribute and link
> to "Web of trust statistics and pathfinder"-Site.
>
> This site provides a statistical analysis of the key (linked behind
> each node) and a path between to keys (linked behind tail and
> head of a edge).
>
> Those URL statements take only affect if one generates IMAP or CMAP
> output and uses this on a HTML-Site as imagemap.