Note that the previous version which allows matrix scaling by a
dimensionedScalarField is not currently correct for asymmetric matrices in
parallel and the transfer of the scaling factor values from the neighbouring
processors is required.

- syntax as per Bourne/Korn shell
      ${parameter:+altValue}

  If parameter is unset or null, nothing is substituted.
  Otherwise the \c altValue is substituted.

small change in constSolidThermo and singleLayerReion