QUICK CLUSTER: Use fixed format for cluster centers.
This command used the variables' own formats for their centers. This was
a bad idea for at least two reasons. First, the variables might have a
format that does not show any decimal places, but clusters wouldn't
ordinarily have integer centers, so this is confusing. Second, if a
cluster center happens to have a value label, it could be shown instead,
which is even more confusing. This fixes the problem by using a fixed
format instead.
Thanks to Andreas Hammer for reporting the problem.