Fix problem when descending order on "Today" and "Thursday" for example. Now we also...

Fix problem when descending order on "Today" and "Thursday" for example. Now we also have week independant maths, so we get a Yesterday tag even if yesterday was 31st and today is 1st. Peter, the
order should be correct now, please recheck (I added a '-', so the order now is the inverse that the one shown on the kfm-devel thread).

CCMAIL: kfm-devel@kde.org

svn path=/trunk/KDE/kdebase/apps/; revision=815341