This systems tests a fully triclinic setup with all three off-diagonal
unit-cell components non-zero, combined with PME. A truncated octahedron
unit-cell is used for this, as this shape is relatively common.
Especially the complex domain decomposition (in particular 1D decomposition)
and the PME code contain a lot of PBC specific code. Most of the other
algorithms and the analysis tools use the standard PCB routines.
