- 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.

Improvements to token handling

See merge request Development/OpenFOAM-plus!160

STYLE: Corrected file name in surface noise, added README file

See merge request Development/OpenFOAM-plus!161

- 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

Feature mesh stitching

See merge request OpenFOAM-plus!159

Improvements to HashTable internals

See merge request Development/OpenFOAM-plus!158

- 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.

- use (value <= VSMALL) instead of (value < VSMALL) for consistency
  with what equal(value, 0) delivers.

- add -compiler=NAME option to remove a build or platforms directory
  corresponding to any specified compiler on the current arch.

- when -compiler or -compiler=NAME is specified, also clean related
  sub-directories as well. This will cleanup mpi-related directory.

- 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()

Feature dictionary scoping lvalue

See merge request OpenFOAM-plus!124