Fixed 0003440: "Allowed File Types" is case sensitive (also applies to disallowed file types).

M core/file_api.php

• Use case-insensitive comparison when checking extensions against allowed/disallowed types.

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@2329 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9