- bundled of boolean values as a vector of 3 components with
  element access using x(), y() and z() member functions.
  It also has some methods similar to bitSet.

- Not derived from Vector or VectorSpace since it does not share very
  many vector-like characteristics.

- support construct from initializer_list, which can help simplify
  code with constant coefficients.

- add default constructor for polynomialFunction and Istream reading
  to support resizable lists of polynomialFunction.

  A default constructed polynomialFunction is simply equivalent to
  a constant zero.

- no special IO handling for Polynomial required,
  it is the same as VectorSpace anyhow.

- previously introduced `getOrDefault` as a dictionary _get_ method,
  now complete the transition and use it everywhere instead of
  `lookupOrDefault`. This avoids mixed usage of the two methods that
  are identical in behaviour, makes for shorter names, and promotes
  the distinction between "lookup" access (ie, return a token stream,
  locate and return an entry) and "get" access (ie, the above with
  conversion to concrete types such as scalar, label etc).

- Favour use of argList methods that are more similar to dictionary
  method names with the aim of reducing the cognitive load.

  * Silently deprecate two-parameter get() method in favour of the
    more familiar getOrDefault.
  * Silently deprecate opt() method in favour of get()

  These may be verbosely deprecated in future versions.

- centralizes sizing information and typedefs
  without dependencies beyond <cstdint>

COMP: ensure label typedef exists for nullObject.H

STYLE: adjust code comments

- similar to the behaviour of std::ignore and consistent with the
  no input / no output nature of nullObject. Similarly accept a
  const reference for its Istream operator.

- make most nullObject methods constexpr

- mostly wraps std::chrono so can inline much of it, which is potentially
  helpful when used for inner timings.

- add elapsedTime() method for direct cast to double and for
  naming similarity with wall-clock method.

Potential breaking change (minor):

- clockValue construct with a bool parameter is now simply tagged
  dispatch (value is ignored) and always queries the current clock
  value. This avoids needless branching.
  Since this constructor form has primarily been used internally (eg,
  clockTime), breakages in user code are not expected.

- have printBuildInfo output to std::ostream
- removed extraneous include "stdFoam.H"

ENH: revert to pre-processor defines for hard-coded paths (#1712)

- redundant information, but more robust at run-time without relying
  on initialization order

- exhibited apparent issues with initialization order (on some
  installations of gcc-4.8.5) when a variable was used.

- previously relied on presence/absence of command-line options.
  Can now explicitly disable individually

- provide shorter constructors for dealing with these types of cases.
  Make construction with non-default names for "system" and "constant"
  lengthier so there is no ambiguity.

For example,

    const edge meshE(patch.meshPoints(), patch.edges()[edgei]);

- enumerated values are (points | topology) which can be optionally
  specified in the blockMeshDict. Default is 'topology'.

  If the command-line option `blockMesh -merge-points` is specified,
  this has absolute priority over any blockMeshDict entry.

STYLE: changed blockMesh "-blockTopology" option to "-write-obj"

- this is more specific to what it does. Potentially wish to add a
  "-write-vtk" option in the future.

TUT: adjust tutorials to use preferred or necessary merge strategies:

  * channel395DFSEM - topology
  * nozzleFlow2D - points
  * pipeCyclic - points

- initial split of wmake-related commands into "plumbing" and
  "porcelain" akin to how git handles things.

- wmakeBuildInfo (very low-level), now relocated to the wmake/scripts
  and accessible for the user as "wmake -build-info".

  This satisfies a long-standing desire to access build information
  in a fashion similar to the api/patch information.

CONFIG: avoid git information when building with a debian/ directory

- when a 'debian/' directory exists, there is a high probability that
  the '.git/' directory is from debian and not from OpenFOAM (ie,
  useless here). This corresponds to an implicit '-no-git', which has
  no effect when building from pristine sources.

ENH: wmakeCheckPwd becomes scripts/wmake-check-dir

- accessible for the user as "wmake -check-dir" and with 1 or 2
  directory names. A wmakeCheckPwd symlink left for compatibility.

- less frequently used, but the information was previously inaccessible
  under etcFiles.C.

  Now exposed within the foamVersion namespace and defined under
  <global.Cver> to improve configuration possibilities.

- less confusing than the env() name, which could look like a
  setter/getter instead of a test

- this specifically arises in the case we have used the `#eval` syntax
  to generate a value.
  However, since the expressions produce scalar/vector/tensor etc, the
  tokenized value will *not* be introduced into the dictionary as a
  label, even if it appears to be an integer value.

  Eg, eval "2*5", eval "sqrt(100)" both yield `scalar(100)`, which
  will not be suitable for any consumer expecting a label value.

  With the `#calc` version, this problem is glossed over since it uses a
  string buffer for the output (which can suppress the decimal)
  and re-parses the string into tokens, which causes a label to be
  recognized.

- Since we obviously already support implicit handling of ints as
  floats (when reading), now also allow conversion of float
  representations of integral values.

  Uses the ad hoc value of 1e-4 for deciding if the value deviates too
  far from being integral.

- As a side-effect, can now also support scientific notation when
  specifying integers.  Eg, (10 100 1e+3) for cell counts.

- were deprecated via comments (2018-10).
  Now mark with compilation warning

- simplified templating, which cleans up code and does not appear to
  break any normal user coding.

ENH: unique_ptr instead of homegrown demand-driven handling.

- allows easier identification for future changes

- preliminary to further changes (#1675)

- takes a search string and a replacement character.
  The replacement character can also be a nul char ('\0'), which
  simply removes the characters.

  Possible uses:

  * Replace reserved characters
      str.replaceAny("<>:", '_');

  * Remove shell meta-characters or reserved filesystem characters
      str.replaceAny("*?<>{}[]:", '\0');

- construct from dimensioned/value, defaulting name from value.
  Can be convenient for these type of operations:

      max(.., dimensionedScalar(somedims, 0.5))

- construct from dimensioned/one, forwarding to pTraits::one.
  Can be convenient for constructors:

    volScalarField( ..., dimensionedScalar(somedims, one{}))

ENH: minor updates to zero/one classes.

- add global 'One' constant for symmetry with 'Zero'.