output: Correctly define and properly implement column width ranges.

output: Correctly define and properly implement column width ranges.

I previously had the idea that SPV files had ranges for both column
widths and row heights, which didn't really make sense, since if
you fix the range of one of those you have to be flexible about the
other.  However, these settings actually control just column widths,
in two sets of columns: the columns for row headings and the columns
for column headings.  This implements those properly.