If I sort first by line, then by file, I should see all the results ordered by file first and line number second.

Currently, the sorting isn't stable, so I can either sort by line number (useless across files), or I can sort by file with the line results in some random order by line number.

A stable sort would make the table much more useful when there are many results as is the case when you first begin running cppcheck on a large code base.