ENH: support change of Pstream buffer format via flag modifier

See merge request OpenFOAM-plus!166

Feature field average windowing

See merge request OpenFOAM-plus!165

- allows changing the format of the sending OPstream at an arbitrary
  point in the transmission. The information is passed through the
  buffer and the receiving IPstream changes its format accordingly.
  This allows a temporary toggling of ASCII/BINARY mid-stream.

- support when creating modules for OpenFOAM.
  Original source from Ivan Spisso (CINECA) modified by OpenCFD

- the return value signals if this method handled this particular type
  of token. This minor change allows this method to be used as a succinct
  prefilter an output token stream. It also provides better encapsulation
  of what the particular output stream handles.

  Eg,

      bool ok = os.write(tok);
      if (!ok)   // or   if (!ok && os.good())
      {
          os << tok;
      }

  instead of

      if (tok.type() == typeA || tok.type() == typeB || ...)
      {
          os.write(tok);
      }
      else
      {
          os << tok;
      }

dictionary compatibility/migration methods

See merge request OpenFOAM-plus!162

- 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 OpenFOAM-plus!160

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

See merge request 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

Also updated/corrected restart behaviour

When specifying the averaging data, a new `windowType` option is
available, taking the values:

- none: no windowing
- approximate: past functionality (v1706 and earlier)
- exact: exact moving average - will store and write (for restart) all
  fields in the window

Feature mesh stitching

See merge request OpenFOAM-plus!159

Improvements to HashTable internals

See merge request OpenFOAM-plus!158