Evaluate best way to handle PHP deprecation of ereg_replace and eregi_replace function in PHP 5.3.0

With the MRBS block I was recently alerted to the PHP deprecation (as of 5.3.0) of ereg_replace. It looks like through most of Moodle 2.0 the ereg_replace and eregi_replace calls have been replaced with preg_replace; however, a search of the code base shows that it is still present in some places in Moodle 2.0 and widely through 1.9. Since preg_replace is PHP 4 compatible it seems safe to just replace it but with PHP 5.3.0 being the current stable release it seems important to make sure we clean up the code so as to avoid folks getting the deprecation warnings. Peace - Anthony