Creates a user in Moodle.
ADD USER <username> IDENTIFIED BY "<password> HAVING
firstname: "<firstname>"
lastname: "<lastname>"
email: "<email>"
[ idnumber: "<idnumber>"
department: "<department"
... ]
ADD USER harry.potter IDENTIFIED BY "f4t3f*z5'e" HAVING firstname: "Harry" lastname; "Potter" email: "harry.potter@poudlard.edu" idnumber: "1ST" department: "Gryffindor"
The current user identifier is set to the id of the created user.