- found() method for consistency with other classes

- operator()(name, deflt) for similarity to lookupOrDefault,
  but without a dictionary

- eliminates previous code duplication and improves maintainability

- split now optionally retains empty substrings.
  Added split on fixed field width.

- Foam::name() now formats directly into string buffer, which a
  removes one layer of copying and also avoids using a non-constexpr
  in the temporary.

STYLE: explicit type narrowing on zero-padded output for ensight

- not maintained and less functionality than ccmToFoam.

- can be used for adjusting option names between versions

- in most cases already checked valid() so don't need additional check
  for setting an existing pointer

- this makes them applicable to Foam::string, Foam::word etc

ENH: improvements to CStringList

- add strings() sublist variant which can be useful when handling
  command arguments separately

- add construct from SubStrings.

- the dictionary-driven variant of stitchMesh allows sequential
  application of 'stitch' operation with requiring intermediate
  writing to disk.

- Without arguments:
  * stitchMesh uses a system/stitchMeshDict or -dict dict

- With arguments:
  * master/slave patches specified on the command-line as in previous
    versions.

- constructor for empty cell/face/point Zones, with contents to be
  transferred in later.

- ZoneMesh::operator(const word&) to return existing zone or a new empty one.

- this provides a better typesafe means of locating predefined cell
  models than relying on strings. The lookup is now ptr() or ref()
  directly. The lookup functions behave like on-demand singletons when
  loading "etc/cellModels".

  Functionality is now located entirely in cellModel but a forwarding
  version of cellModeller is provided for API (but not ABI) compatibility
  with older existing user code.

STYLE: use constexpr for cellMatcher constants

- makes for clearer code

ENH: make writeIfDifferent part of Ostream

- reduces ambiguity between matching a list of strings and a single string.

- when dictionary keywords change between versions, the programmer
  can use these compatibility methods to help with migration.

    * csearchCompat, foundCompat, lookupEntryPtrCompat, lookupEntryCompat,
      lookupCompat, lookupOrDefaultCompat, readIfPresentCompat, ...

  They behave like their similarly named base versions, but accept an
  additional list of older keyword names augmented by a version number.
  For example,

      dict.readIfPresentCompat
      (
          "key", {{"olderName", 1612}, {"veryOld", 240}},
          myscalar
      );

   where 1612=OpenFOAM-v1612, 240=OpenFOAM-v2.4.x, etc.

- If the entry could be directly inserted: a pointer to the inserted entry.
- If a dictionary merge was required: a pointer to the dictionary that
  received the entry.
- Return nullptr on any type of insertion failure.

This change is code compatible with existing code since it only alters
a bool return value to be a pointer return value.

- simplify string output code

- improved memory alignment reduces overhead for Int32 compilation

- added move/swap semantics

- made the type() readonly in favour of setVariant() to allow change
  of variant within a particular storage representation.
  Eg, STRING -> VERBATIMSTRING.

- move append() single element to List and DynamicList

ENH: add stringOps::count to avoid unnecessary string conversions

- support send/receive with embedded '\0' characters

- avoid meshModifier contents from being read immediately upon
  construction, since this recreates an existing modifier instead of
  allowing us to specify our own.

- make single-parameter construct (label) explicit
- consolidate iterators
- slightly reduced overhead for some HashSet types
- improved resizing behaviour
- compact output for empty Ptr hashes

- unused, unmaintained and slower than the regular HashTable

- the zero::null and one::null sub-classes add an additional null
  output adapter.

  The function of the nil class (special-purpose class only used for
  HashSet) is now taken by zero::null.

- consistent with C++ STL conventions, the reverse iterators should
  use operator++ to transit the list from rbegin() to rend().

  The previous implementation used raw pointers, which meant that they
  had the opposite behaviour: operator-- to transit from rbegin() to
  rend().

  The updated version only has operator++ defined, thus the compiler
  should catch any possible instances where people were using the old
  (incorrect) versions.

- updated forAllReverseIters() and forAllConstReverseIters() macros to
  be consistent with new implementation and with C++ STL conventions.

- forAllReverseIters and forAllReverseConstIters macros
- stdFoam::rbegin(), stdFoam::rend()
  stdFoam::crbegin(), stdFoam::crend()

- Instead of relying on #inputMode to effect a global change it is now
  possible (and recommended) to a temporary change in the inputMode
  for the following entry.

     #default   : provide default value if entry is not already defined
     #overwrite : silently remove a previously existing entry
     #warn      : warn about duplicate entries
     #error     : error if any duplicate entries occur
     #merge     : merge sub-dictionaries when possible (the default mode)

  This is generally less cumbersome than the switching the global
  inputMode. For example to provide a set of fallback values.

      #includeIfPresent "user-files"
      ...
      #default value uniform 10;

  vs.

      #includeIfPresent "user-files"
      #inputMode protect
      ...
      value uniform 10;
      #inputMode merge    // _Assuming_ we actually had this before

  These directives can also be used to suppress the normal dictionary
  merge semantics:

     #overwrite dict { entry val; ... }