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
F is a number. And F7 as it is defined now is a number with 7 digits before the decimal delimiter and 0 digits after the decimal dilimiter. In other words: a integer with a max value of 9999999.