Updates a shell user.
$session_id, $client_id, $primary_id, $params
Parameters (in $params):server_id (int(11))
parent_domain_id (int(11))
username (varchar(64))
password (varchar(64))
quota_size (bigint(20))
active (enum('n','y'))
puser (varchar(64))
pgroup (varchar(64))
shell (varchar(255))
dir (bigint(20))
chroot (int(11))
Output:Returns the number of affected rows.