Include lastpage in export

See http://www.limesurvey.org/en/community-services/forums/can-i-do-this-with-limesurvey/99158-spss-output-error#115427
and
http://bugs.limesurvey.org/view.php?id=9398
Seems ok to me. Don't have time to test it though but it should be ok.