Made some improvements to ACL system including: warning on setting Deny for Everyone on the entire site, added ACL_ALWAYS_ALLOW_ADMIN_EDIT_ACL, and changed behavior as noted in the docs so that Deny for Everyone is no longer able to be overridden

<?php

class Text_Wiki_Render_Plain extends Text_Wiki_Render {
    
    function pre()
    {
        return;
    }
    
    function post()
    {
        return;
    }
    
}
?>