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.

- polyMesh constructor from cell shapes invoked 'removeFiles'.
  This may or may not be what the caller wants or expects.
  With the ParaView blockMesh viewer, this behaviour causes deletion of
  all mesh data (points, faces, etc) when the viewer is refreshed.

  Triggered even when just building the blockMesh topology.

- only a few places that construct a polyMesh from cell shapes
  (mostly mesh conversion utilities).
  Ensure that the file removal (if any) occurs in the application
  and *not* as a side-effect of calling the polyMesh constructor.

--

  blockMesh (application)
    - The placement of the removeFiles seems to also remove freshly
      generated sets (Bug or feature to remove sets?)

  +-----------------------+---------------+------------------+
  | Application           | Constructor   | removeFiles      |
  |                       | (patch info)  | new / existing   |
  +-----------------------+---------------+------------------+
  | blockMesh             | dictionary    | existing         |
  | ansysToFoam           | names         | new              |
  | cfx4ToFoam            | dictionary    | new              |
  | fluentMeshToFoam      | names         | new              |
  | gambitToFoam          | dictionary    | new              |
  | gmshToFoam            | names         | new              |
  | ideasUnvToFoam        | names         | new              |
  | kivaToFoam            | dictionary    | new              |
  | mshToFoam             | names         | new              |
  | netgenNeutralToFoam   | names         | new              |
  | plot3dToFoam          | names         | new              |
  | tetgenToFoam          | names         | new              |
  | vtkUnstructuredToFoam | names         | new              |
  +-----------------------+---------------+------------------+

Surf field sampling

See merge request !87

ENH: runTimePostProcessing - added option to clear/remove objects after use

When specifying line and surface function-object-based visualisation, use the optional `clearObjects` flag to indicate that source objects should be removed/cleared after use.

Test case: [cavity.tgz](/uploads/62cc2761d132f42456f2af08f1499eba/cavity.tgz)

Syntax:

```
    surfaces
    {
        cuttingPlane1
        {
            type            functionObject;
            functionObject  cuttingPlane;
            clearObjects    yes;              // new option
            ...
```

Note: only files that have been used will be removed, e.g. if a function object has created multiple surface files, unused files will remain at the end of the run - in the attached case the p surface remains...

See merge request !89