#2260 in light of #2042 - change from set to vector for send receive buffers

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18873 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2183 / #2382 fix coverage. Removed `NodesOnlyMesh::CalculateNodePairs` as it is now superceeded

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18876 b5f69653-2bf5-0310-8201-b0dafb8e1405
#2367 Fix some more parallel issues.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@18878 b5f69653-2bf5-0310-8201-b0dafb8e1405