#2441 Parallel methods for output of totals from cell populations.  (Breaks archive format.)

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@21899 b5f69653-2bf5-0310-8201-b0dafb8e1405
git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@21900 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2441 Fix archive files wrt r21899

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@21902 b5f69653-2bf5-0310-8201-b0dafb8e1405