BUG: reconstructPar ignores writeLagrangianPositions (fixes #702)

- The central InfoSwitch "writeLagrangianPositions" allows writing an
  additional Lagrangian "positions" file, but these were not being
  written by reconstructPar. These are now also written in reconstructPar
  if the central writeLagrangianPositions InfoSwitch is enabled.

NOTES

- "positions" are reconstructed from the processors "coordinates" file

- decomposePar will not attempt to create or redistribute any
  "positions" files