- adjust comment formatting to reduce clutter

- relocate WM_COMPILER_ARCH, WM_COMPILER_LIB_ARCH from
  etc/{bashrc,cshrc} to etc/config.{csh,sh}/settings since these
  should not be changed by the user anyhow.

- Use gcc/g++ as common base and specialize afterwards (to reduce
  duplication)

- adjust format of WM_PROJECT_SITE fallback to allow for easier
  automated edits

- unknown options or missing option values now emit a shorter message
  without the entire usage. This makes it easier to identify the errors
  and is better aligned with the behaviour of GNU system tools.

  ====
     $ simpleFoam -case
     Using: OpenFOAM-plus (see www.OpenFOAM.com)
     Build: plus-01234

     Error: option '-case' requires an argument

     See 'simpleFoam -help' for usage
  ====

- provide for reduced (-help) and full (-help-full) usage information.
  In many cases the reduced usage provided sufficient and easier
  to find the information.

- make -srcDoc an alias for -doc-source

- no warnings about option aliases for future dates.

- browser is spawned as a background process to avoid blocking the
  command-line

- 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

- unused, unmaintained and slower than the regular HashTable

- the USE_OMP preprocessor symbol is also defined with the openmp
  compile flag to allow conditional compilation of openmp-specific
  code.

- refactor some common metis-like elements into the metisLikeDecomp
  abstract class.

- this compact form shows the subscription per host in the unsorted
  mpi order

      nProcs : 18
      Hosts  :
      (
          (node1 6)
          (node2 8)
          (node3 4)
      )

  This provides a succinct overview of which hosts have been
  subscribed or oversubscribed.

- The longer list of "slave.pid" ... remains available on the
  InfoSwitch 'writeHosts'

- relocate as Test-surfaceMeshConvert.

- the (global) associative array requires bash >= 4.2

- this reduces the number of functions and allows lazy loading of
  completion options, which makes it easy to quickly add any other
  OpenFOAM application in completion.

  The generic '_of_complete_' function handles (bash) completion for
  any OpenFOAM application. On the first call for any particular
  application, it retrieves the available options from the application
  help output and adds this information to its environmental cache for
  subsequent use.

- Tcsh completion uses the same function via a bash wrapper.
  But since its wrapper is transient, the on-the-fly generation would
  be less efficient. For this case, a pre-generated completion_cache
  can be used, which is generated with

      bin/tools/foamCreateCompletionCache

- the cray C/C++ compilers appear to be option-compatible with gcc.

- no wmake rules for 32bit builds (deemed to be unnecessary)

- handles the case where we are currently completing something that
  does not appear to be an option. For example,

      foamDictionary -expanded someD[TAB]

  should complete the filename, not present more options.

- although this has been supported for many years, the tutorials
  continued to use "convertToMeters" entry, which is specific to blockMesh.
  The "scale" is more consistent with other dictionaries.

ENH:
- ignore "scale 0;" (treat as no scaling) for blockMeshDict,
  consistent with use elsewhere.

- currently no cleanup of completions when deactivating an OpenFOAM
  tcsh environment

- tab completion with directories adds a space after the slash, which
  makes navigation a bit annoying.

- use complete -o filenames, dropped -o nospace to make it more responsive.

- restructure completion code to use a unified backend, which makes it easier
  understand, maintain and re-use.

- foamCreateBashCompletions now simply outputs to a stdout, and allows
  quick generation of completion of single applications.

- add -fileHandler completion in anticipation of future changes there.

- relocated as etc/config.s/bash_completion to prevent inadvertently
  having two versions (.com, .org) installed at the same time.

- 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; ... }

- since the cpu/sys information is invariant, it doesn't make much
  sense to emit by default at every time-step.

- With many processors, the number of entries becomes quite large.

  New controlDict InfoSwitches: "writeSlaves", "writeRoots".

old "positions" file form

The change to barycentric-based tracking changed the contents of the
cloud "positions" file to a new format comprising the barycentric
co-ordinates and other cell position-based info.  This broke
backwards compatibility, providing no option to restart old cases
(v1706 and earlier), and caused difficulties for dependent code, e.g.
for post-processing utilities that could only infer the contents only
after reading.

The barycentric position info is now written to a file called
"coordinates" with provision to restart old cases for which only the
"positions" file is available. Related utilities, e.g. for parallel
running and data conversion have been updated to be able to support both
file types.

To write the "positions" file by default, use set the following option
in the InfoSwitches section of the controlDict:

    writeLagrangianPositions 1;

- added an explicit print, but only report profiling to the log
  file from master process.

  We don't wish to overwrite any profiling that was conducted during
  the simulation. Besides which, we don't have a proper Time object
  for handling the write nicely either.

- add note in BuildIssues about the I_MPI_CC variable, which is needed
  when building with Intel-MPI and gcc/clang.

  This additional setting is needed since the changes needed to solve
  the issue of building scotch with Intel-MPI and icc (issue #434)
  means that mpiicc is now being used as the wrapper when compiling
  scotch.

- have the FOAM_MPI short name for INTELMPI start with 'impi-' instead
  of just the version number.
  Intel-MPI is often installed as /opt/intel/impi/4.1.3.049, which
  results in 'FOAM_MPI=4.1.3.049' and the mpi flavour is lost.
  Prefix these cases with 'impi-'

- Added for transition purposes only in 1612 but can now be removed.