- don't need extra nullptr check for some cases. Less clutter.

- changed for 1906 to have a regIOobject always cleanup its
  objectRegistry entry. No need to explicitly 'release' ownership
  for this to now happen.

- doxygen formatting for MeshObject

Caveat: The -Wdeprecated-copy produces many, many compiler warnings

TODO: need to revisit

- if desired to create a tar-file without a _patch value in its name.

- add a '-SPDP' option

- remove the '-archOption' for forcing a '-m32' build on 64-bit
  architecture, which is now considered too obscure.
  Must edit files manually if this option is really required.

Digital-Filter Based Synthetic Turbulence Generation Method for LES/DES Inflow

See merge request OpenFOAM-plus!235

 Please enter the commit message for your changes. Lines starting

The following three synthetic turbulence inflow boundary conditions are
examined through single-cell-domain smooth-wall plane channel flow setup:

- turbulentDFSEMInlet
- turbulentDigitalFilterInlet variant=digitalFilter
- turbulentDigitalFilterInlet variant=reducedDigitalFilter

The examinations are performed in terms of the first-/second-order turbulence
statistics provided by (Moser et al., (1999)) doi.org/10.1063/1.869966
from smooth-wall plane channel flow direct numerical simulations at Re=395.

Serial executing:

./Allrun

Parallel (decompositionMethod=scotch) executing:

./Allrunparallel