Let add users via the list of users in the similar manner it’s
done for networks. It’s evidently an extra step to add a user,
but on the other hand it gives a nice overview of the users
when adding new ones, and leads to less clutter in the sidebar.
Prefix links in templates with URIPrefix and add the input field to the
Listener editor.
The URIPrefix is provided as a top-level template variable. All URIs
have been changed to have the prefix prepended.
