- minor simplification of #if/#endif handling

ENH: improve input robustness with negative-prefixed expansions (#2095)

- especially in blockMeshDict it is useful to negate an value directly.
  Eg,
  ```
     xmax  100;
     xmin  -$xmax;
  ```
  However, this fails since the dictionary expansion is a two-step
  process of tokenization followed by expansion. After the expansion
  the given input would now be the following:
  ```
     xmax  100;
     xmin  - 100;
  ```
  and retrieving a scalar value for 'xmin' fails.

  Counteract this by being more generous on tokenized input when
  attempting to retrieve a label or scalar value.
  If a '-' is found where a number is expected, use it to negate the
  subsequent value.

  The previous solution was to invoke an 'eval':
  ```
     xmax  100;
     xmin  #eval{-$xmax};
  ```
  which adds additional clutter.

ENH: splitMeshRegions: combine cellZones. See #2046

See merge request !448

refactor and extend handling of faSchemes/fvSchemes

See merge request !449

- use common base for handling scheme lookups.
  Extended to support local injection of schemes into the dictionaries
  during runtime.

- add const qualifiers on C() methods

collected changes for Lists, faces and PrimitivePatch

See merge request !446

- intended for the following type of use:

      auto oldHandler = fileHandler(fileOperation::NewUncollated());

      ... do something that only works with uncollated

      // Restore previous (if any)
      if (oldHandler)
      {
          fileHandler(std::move(oldHandler));
      }

ENH: make fileOperation distributed(bool) mutable

- use is "static-like" and akin to Pstream::parRun(bool),
  thus allow toggling of the switch without a const_cast

- use polyMesh::defaultRegion instead of fvMesh::defaultRegion and
  others via static inheritance. (92 vs ~25 occurrences)

- return internalEdges() and boundaryEdges() sub lists directly

- calculate and return boundaryFaces() to identify faces attached to
  boundary edges.

- minor code cleanup, and add PrimitivePatchBase class for
  non-templated code.

STYLE: mark unused parameter in globalMeshData mergePoints

- copy assignment from indirect list to SubList and Field

- this constructor was added for similarity with std::vector,
  but continues to cause various annoyances.

  The main problem is that the templated parameter tends to grab
  anything that is not a perfect match for other constructors.

  Typically seen with two integers (in 64-bit mode), but various other
  cases as well.

  If required, the ListOps::create() function provides a lengthier
  alternative but one that can also incorporate transformations.
  Eg,

      pointField pts = ....;

      List<scalar> mags
      (
          List<scalar>::create
          (
              pts.begin(),
              pts.end(),
              [](const vector& v){ return magSqr(v); }
      );

- improves interchangeability of List vs IndirectList

- additional rcEdge(), rcEdges() methods for reverse order walk

- accept generic edge() method as alternative to faceEdge() for
  single edge retrieval.

- edge() method with points -> returns the vector

- reduce the number of operations in edgeDirection methods

DEFEATURE: remove longestEdge global function

- deprecated and replaced by face::longestEdge() method (2017-04)

- gcc-4.8.5 does not respect the default parameter,
  thus specify format explicitly

Historically the "geometry" for static meshes was placed under
directly in the EnSight case directory.

Eg,

     ensight/ensight.case
     ensight/geometry
     ensight/data/000001
     ensight/data/000002 ...

This generally works ok, but relocating it to a constant data directory
Eg
     ensight/ensight.case
     ensight/data/constant/geometry
     ensight/data/000001
     ensight/data/000002 ...

Improves handling and avoids potential collisions when adding in
additional mesh regions

- reduces code, simplifies creation of new, specialized polyData
  writers.

- new templated vtk::GenericPatchWriter, which adds support for
  writing both uindirectPrimitivePatch + indirectPrimitivePatch types.

- handle geometric fields separately from regular fields with
    * vtk:GenericPatchGeoFieldsWriter
    * vtk:indirectPatchGeoFieldsWriter
    * vtk:uindirectPatchGeoFieldsWriter

- can be used for block-like meshes that are not aligned with the global
  coordinate directions. Alternatively, for general testing purposes.

  Example,

    method  simple;
    coeffs
    {
        n       ( 2 2 2 );
        transform
        {
            origin  (-0.15 0.15 0);
            e1      (1 1 0);
            e3      (0 0 1);
        }
    }

add multi-region handling for checkMesh etc,  centralized the region handling #2072

See merge request !445

Step 1.
    include "addAllRegionOptions.H"

    Adds the -allRegions, -regions and -region options to argList.

Step 2.
    include "getAllRegionOptions.H"

    Processes the options with -allRegions selecting everything
    from the regionProperties.

    OR use -regions to specify multiple regions (from
       regionProperties), and can also contain regular expressions

    OR use the -region option

    Specifying a single -regions NAME (not a regular expresssion)
    is the same as -region NAME and doesn't use regionProperties

    Creates a `wordList regionNames`

Step 3.
    Do something with the region names.
    Either directly, or quite commonly with the following

    include "createNamedMeshes.H"

    Creates a `PtrList<fvMesh> meshes`

STYLE: add description to some central include files

- useful for establishing and preallocating a max buffer size
  when reading from sub-procs

improve flexiblity of IOdictionary construction, use of ITstream, Function1

See merge request !444

- make regionName an optional constructor parameter, which eliminates
  a separate set of constructors and construction tables. Adjust
  internals to treat a missing/empty regionName as a no-op.

- pass in fallback dictionary content via new IOdictionary constructor
  with a pointer

ENH: further relax check for matching number of processor dirs

- if the "numberOfSubdomains" entry is missing (or even zero)
  ignore checks of processor dirs as meaningless.

- additional debug information

- improve support for dictionary specification of constant, polynomial
  and table entries. These previously only worked properly for
  primitiveEntry, which causes confusion.

- extend table Function1 to include TableFile functionality.
  Simplifies switching and modifying content.

- can construct named empty dictionary directly.
- removed some duplicate code

- failsafe examine elements: peek(), peekFirst(), peekLast()
- failsafe traversing: skip()

  For example,

      ITstream& is = dict.lookup(key);
      if (is.peek().isWord())
      {
          is.skip();
      }

- additional default construct

- add explicit zero-size constructor for ITstream.
  For tagged dispatching, without ambiguity

- elminate mandatory name for parsing versions.
  This makes it easier to use ITstream, IStringStream, UListStream
  interchangeable.

- return undefinedToken on error

STYLE: fix slicing of ITstream from dictionary lookup