query_users.php is modified even if we will drop it in the future to be sure it works everywhere.
- replaced <? with <?php for compatibility sake (see TODO and CODING_STANDARD to know more) - improved overall code lisibility
- fix some code errors and typos (missing $ in front of variable names and so on) - fixed a lot of warnings that would have been thrown when error_reporting is set to show notices (if(isset($variable))) instead of if($variable) for example)
