- writes positions and a single field (eg, diameter) in plain ASCII files,
  suitable for importing in a spreadsheet or manipulation with
  scripting tools.

- code integrated from
  https://develop.openfoam.com/Community/OpenFOAM-addOns

  New name:  findObject(), cfindObject()
  Old name:  lookupObjectPtr()

      Return a const pointer or nullptr on failure.

  New name:  findObject()
  Old name:  --

      Return a non-const pointer or nullptr on failure.

  New name:  getObjectPtr()
  Old name:  lookupObjectRefPtr()

      Return a non-const pointer or nullptr on failure.
      Can be called on a const object and it will perform a
      const_cast.

- use these updated names and functionality in more places

NB: The older methods names are deprecated, but continue to be defined.

- similar to the \c <=> operator in C++20.
  Primarily for use when defining cascaded sort function objects.

- these currently only with bool parameters, but the return value should
  nonetheless always be a bool value:

      andOp(), orOp(), lessOp(), lessEqOp(), greaterOp(), greaterEqOp()

- renamed the unused eqEqOp() to equalOp() for naming consistency with
  the equal() global function.

ENH: equalOp() specialization for scalars

- function object version of the equal() function.
  The default constructor uses the same tolerance (VSMALL),
  but can also supply an alternative tolerance on construction.

This is the additional fix to make dynamic unrefinement work again.

Description
    Calculates the spatial minimum and maximum extents of a field

    The extents are derived from the bound box limits after identifying
    the locations where field values exceed the user-supplied threshold
    value.

Usage
    Example of function object specification:

    fieldExtents1
    {
        type        fieldExtents;
        libs        ("libfieldFunctionObjects.so");
        ...
        writeToFile yes;
        log         yes;
        fields      (alpha);
        threshold   0.5;
        patches     ();
    }

    Where the entries comprise:

        Property      | Description              | Required   | Default
        type          | type name: fieldExtents  | yes        |
        writeToFile   | write extents data to file | no       | yes
        log           | write extents data to standard output | no | yes
        internalField | Process the internal field | no       | yes
        threshold     | Field value to identify extents boundary | yes |
        referencePosition | Reference position   | no         | (0 0 0)
        fields        | list of fields to process | yes       |
        patches       | list of patches to process | no       | <all>

    Output data is written to the file \<timeDir\>/fieldExtents.dat

Note
    For non-scalar fields, the magnitude of the field is employed and
    compared to the threshold value.

- Eg,
    scalar val(-GREAT);

    const entry* eptr = dict.findEntry(k);

    if (eptr)
    {
        val = eptr.get<scalar>();

        // Or
        eptr.readEntry(val);
    }

- was "solver" in 1612 and "motionSolver" for later versions

- clarifies the meanings of get<T> etc, avoids later ambiguities.

ENH: simplify phaseProperties construction, add input checks

- with the 'cwd' optimization switch it is possible to select the
  preferred behaviour for the cwd() function.

  A value of 0 causes cwd() to return the physical directory,
  which is what getcwd() and `pwd -P` return.
  Until now, this was always the standard behaviour.

  With a value of 1, cwd() instead returns the logical directory,
  which what $PWD contains and `pwd -L` returns.
  If any of the sanity checks fail (eg, PWD points to something other
  than ".", etc), a warning is emitted and the physical cwd() is
  returned instead.

  Apart from the optical difference in the output, this additional
  control helps workaround file systems with whitespace or other
  characters in the directory that normally cause OpenFOAM to balk.
  Using a cleaner symlink elsewhere should skirt this issue.

  Eg,
      cd $HOME
      ln -s "/mounted volume/user/workdir"  workdir
      cd workdir
      # start working with OpenFOAM

- foamCleanPath now only splits the environment variable on ':', which
  allows other directories with spaces or '(..)' etc to pass through
  without major issue.

- The filter arguments are split on whitespace, colons or semi-colons.

- use keyType::option enum to consolidate searching options.
  These enumeration names should be more intuitive to use
  and improve code readability.

    Eg,   lookupEntry(key, keyType::REGEX);
    vs    lookupEntry(key, false, true);

  or

    Eg,   lookupEntry(key, keyType::LITERAL_RECURSIVE);
    vs    lookupEntry(key, true, false);

- new findEntry(), findDict(), findScoped() methods with consolidated
  search options for shorter naming and access names more closely
  aligned with other components. Behave simliarly to the
  methods lookupEntryPtr(), subDictPtr(), lookupScopedEntryPtr(),
  respectively. Default search parameters consistent with lookupEntry().

    Eg, const entry* e = dict.findEntry(key);
    vs  const entry* e = dict.lookupEntryPtr(key, false, true);

- added '*' and '->' dereference operators to dictionary searchers.

- seen with gcc-4.9.4, but not with gcc-7

- provide additional constructors from tmp for DimensionedField, FieldField

- use the dictionary 'get' methods instead of readScalar for
  additional checking

     Unchecked:  readScalar(dict.lookup("key"));
     Checked:    dict.get<scalar>("key");

- In templated classes that also inherit from a dictionary, an additional
  'template' keyword will be required. Eg,

     this->coeffsDict().template get<scalar>("key");

  For this common use case, the predefined getXXX shortcuts may be
  useful. Eg,

     this->coeffsDict().getScalar("key");

- not used by the ISstream parser, but suitable for other parsing
  methods where true/false concept should be distinguishable from
  integer values.

  Only constructed via the token::boolean() static method, not
  directly assignable.
  This avoids any potential ambiguities with label.

coordinate system improvements

See merge request OpenFOAM-plus!211

- avoids some doubled slashes

STYLE: simplify concatenation of processor directory names

- adjust member order in TimePaths to better packing

- local token shifting was missing when getting the next file chunk
  (while in the middle of parsing that text).

  As well as adding the correct shifting, also tag the local buffer
  with nullptr when it is done. Be extra paranoid and check the
  raw buffer range before passing off to std::string.

- for finer control of the '-help' output text

- this also removes the '-newTimes' option cruft from appearing
  everywhere. reconstructPar and redistributePar are unaffected by this
  since they define their own -newTimes option independently.

Compilation problems on older compilers

This reverts commit baf3e931.

    UPtrList::set(const label i, T* ptr);

No-op if the new pointer value is identical to the current content.
This avoid memory management issues.