This slightly more convenient when working with char[] input:

     fileName file1{ "path", "name", "to", "file.ext" };
vs.  fileName file1 = fileName(path)/"name"/"to"/"file.ext";

But is a bit more efficient since it avoid most of the intermediate
copying and resizing incurred by the '/' operator.

- not required for ASCII, and makes normal dictionaries too noisy.

STYLE: move archHint to be a file-scope static

- Use wordRe::REGEXP (not wordRe::DETECT) if the content is known to
  be a regular expression anyhow.

Bounding thermo.rho in rhoPorousSimpleFoam.
Changing initial time step in externalSolarLoad tutorial.
Commenting out momemtun source term in steamInjection which causes problems

  FoamFile
  {
      version     2.0;
      format      binary;
      arch        "LSB;label=32;scalar=64";
      class       vectorField;
      object      points;
  }

There is otherwise no simple indication in any of the files as to the
sizes used (Int32 vs Int64, SP vs DP). This makes it difficult for the
end-user and also for any third-party consumers.

--
The architecture information contains three items in the following format:

    (LSB|MSB);label=(32|64);scalar=(32|64)

- The endian value always appears first, without any leading space.
  This make it trivial to check later. Either the first 3 letters (LSB
  vs MSB) or even just the first letter ('L' vs 'M').

- Subsequent key=value pairs for 'label' and 'scalar' are separated
  by semicolons. The ordering of label vs scalar is not specified.

Note that this 'arch' information is purely informational.
It is currently not used by the OpenFOAM input mechanism itself.

- can adjust many more values

- sometimes used for off-screen rendering.
  Only add to library-path when they are actually available

added optional argument description (Fixes #347)

Optional argument listed.

@andy @mark Could you confirm/merge?

See merge request !90

- The value from -outputThreshold was used in the code,
  but the option definition itself was somehow missed.