XMLStatistic macro, sort alphabetically file names to order the columns in the result table

Currently, the columns in the result table is in no order.

This prevents the analysis of different versions of the same file and doesn’t help to read the result table.

Solution

• order the columns in the result table alphabetically by file name.

(from redmine: issue id 3074, created on 2021/05/20 by Serge Heiden)