Code formatting.
Added test against neighbor relationships for a refinement sequence in which MeshTopology was getting it wrong.
More work on MeshTopology, etc.  MeshTopology now passes the new test.  Reduced memory footprint of MeshTopology slightly (3% or so) by eliminating storage of subcell indices from Cell.
Merge branch 'master' of https://github.com/CamelliaDPG/Camellia