#2441 - use BOOST_FOREACH (c.f. r21484)

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@21493 b5f69653-2bf5-0310-8201-b0dafb8e1405
git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@21495 b5f69653-2bf5-0310-8201-b0dafb8e1405