Changed the order of the icons that indicate sorting order to conform to the UI convention used in most software:
up arrow indicates ascending sorting order
down arrow indicated descending sorting order

Modified Files:
core/icon_api.php

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@1793 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9