Returns array:
associative array of users of ONE realm if $inRealm was supplied <pre> realm1 + user1 => pass + user2 => pass + user3 => pass </pre>
associative array of all realms with all users <pre> array + realm1 => array + user1 =&gt; pass + user2 =&gt; pass + user3 =&gt; pass + realm2 => array + user3 =&gt; pass + realm3 => array + user1 =&gt; pass + user2 =&gt; pass </pre>