NewNewUser()/newuser would block and then unblock and get done; meanwhile the PHP
thread went away so we never returned to call NewNewProject/mkproj.  Move the call
on the newuser script from PHP into the back-end Perl newproj script for atomicity.

    www/newproject.php3 - When the project leader is a new user, pass two xml
        files to the newproj backend script, one describing the project and the
        second one (an optional) file describing the newuser.

    www/user_defs.php - Factor the xml-making part of NewNewUser into NewNewUserXML.

    www/project_defs.php - Remove the required $leader arg of NewNewProject.
        newproj may call newuser, which may generate the leader uid.

    backend/newproj.in - Call newuser with an optional 'newuser_xml' XML file.

    sql/database-fill.sql - Add 'projects','newuser_xml'.