Fix 0003252: Category not selected on update if "&" is used in category name.

M core/print_api.php

• Use string_attribute() on strings before outputting them to html and calling check_selected(). [the fix is not yet tested]

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@2207 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9