Bug Fix:#3813 grid editing utf8 set/enum value

With this it solves every bugs displays here (https://sourceforge.net/p/phpmyadmin/bugs/3813/#0518) for me.
The change of  phpmyadmin\libraries\Util.class.php is to prevent , having unwanted characters like https://sourceforge.net/p/phpmyadmin/bugs/3813/#0518.
Check more if there are other test cases.