- preferentially handle Allwmake.override, which allows packaging
  tools to define alternative make scripts, or selectively disable
  components.

- remove legacy handling of 'Optional' directory.
  Conditionals have since migrated into scripts themselves and/or
  use the wmake/scripts/have_* framework.

BUG: missed passing -debug for Allwmake scripts

- simplifies code, covers most cases.
  Can use wmake -show-api or wmakeBuildInfo to query the make rules.

STYLE: Allwmake script adjustments

- use bin/foamEtcFile instead of relying on PATH.
  The make environment may not have the OpenFOAM bin/ in it.

- simpler shell syntax

- previously just reported gcc/clang versions, but these are not
  necessarily the ones actually being used (eg, clang-9 vs clang).
  Now use the path from `wmake -show-path-cxx` to improve the accuracy,
  and also support other compiler types.

- an empty WM_COMPILE_OPTION is treated internally (in make rules)
  like "Opt"

- an empty WM_COMPILER_TYPE is treated like "system" (system compiler)

- can assist diagnosing when things have gone wrong

- no use having wmkdepend on the target architecture when it will only
  be needed on the host architecture.

- report api, patch as well as the number of entries in the
  FOAM_APPBIN, FOAM_LIBBIN for a quick visual sanity check

- provide default WM_DIR if not already set, to improve robustness if a
  reduced environment is used

- add etc/ to WM_PROJECT_SITE search. This makes the site directory
  structure consistent with the OpenFOAM structure.
  Eg,

      WM_PROJECT_SITE/etc/..
      WM_PROJECT_SITE/bin/..
      WM_PROJECT_SITE/platforms/..

- Don't set/export WM_OSTYPE.  The default is POSIX and is properly
  defaulted throughout, including in CMakeLists-OpenFOAM.txt (also for
  Catalyst)

- convenient when bootstrapping some systems

- provides some feedback about which mpi is being used

- any code placed here should provide Allwmake and Allwclean scripts
  and normally have compilation targets into FOAM_APPBIN, FOAM_LIBBIN

  Since there is no standardize places for sources or applications,
  a simultaneous build of a module's doxygen documentation requires
  a minor bit of manual effort. Add (via symlink) the sources into
  the modules/doc/ directory to have them included in the normal
  OpenFOAM doxygen documentation generation.

  A makelink.example file is provided there as an example.

- generalize some of the library extensions (.so vs .dylib).
  Provide as wmake 'sysFunctions'

- added note about unsupported/incomplete system support

- centralize detection of ThirdParty packages into wmake/ subdirectory
  by providing a series of scripts in the spirit of GNU autoconfig.
  For example,

      have_boost, have_readline, have_scotch, ...

  Each of the `have_<package>` scripts will generally provide the
  following type of functions:

      have_<package>          # detection
      no_<package>            # reset
      echo_<package>          # echoing

  and the following type of variables:

      HAVE_<package>          # unset or 'true'
      <package>_ARCH_PATH     # root for <package>
      <package>_INC_DIR       # include directory for <package>
      <package>_LIB_DIR       # library directory for <package>

  This simplifies the calling scripts:

      if have_metis
      then
          wmake metisDecomp
      fi

  As well as reducing clutter in the corresponding Make/options:

      EXE_INC = \
          -I$(METIS_INC_DIR) \
          -I../decompositionMethods/lnInclude

      LIB_LIBS = \
          -L$(METIS_LIB_DIR) -lmetis

  Any additional modifications (platform-specific or for an external build
  system) can now be made centrally.

- just check WM_PROJECT_DIR instead.

- provide a fallback value when FOAM_EXT_LIBBIN might actually be needed.

Only strictly need FOAM_EXT_LIBBIN for scotch/metis decomposition, and
when these are actually supplied by ThirdParty.
All other ThirdParty dependencies are referenced by BOOST_ARCH_PATH etc.

Can therefore drop the FOAM_EXT_LIBBIN dependency for VTK-related
things, which do not use scotch/metis anyhow.

- minor bug: 'wclean empty' may have had issues with logical vs physical path

- easier to test or use different versions

- change WM_CXXFLAGS to -std=c++11 instead of -std=c++0x

Patch contributed by Bruno Santos
Resolves patch request https://bugs.openfoam.org/view.php?id=2424

- this is apparently not uniform across systems

STYLE: unify the date format in logfile

- Could be related to interrupted builds.
  So if there are any parts of the build that rely on an explicit
  'wmakeLnInclude', make sure that the contents are properly updated.

--

ENH: improved feedback from top-level Allwmake

- Report which section (libraries, applications) is being built.

- Provide final summary of date, version, etc, which can be helpful
  for later diagnosis or record keeping.

- The -log=XXX option for Allwmake now accepts a directory name
  and automatically appends an appropriate log name.
  Eg,
      ./Allwmake -log=logs/  ->> logs/log.linux64GccDPInt32Opt

  The default name is built from the value of WM_OPTIONS.

--

BUG: shell not exiting properly in combination with -log option

- the use of 'tee' causes the shell to hang around.
  Added an explicit exit to catch this.

--

- Detecting the '-k' (-non-stop) option at the top-level Allwmake, which
  may improve robustness.

- Explicit continue-on-error for foamyMesh (as optional component)

- unify format of script messages for better readability

COMP: reduce warnings when building Pstream (old-style casts in openmpi)

It is better to run doc/Allwmake or doc/Doxygen/Allwmake and provide the
required options.

Patch contributed by Mattijs Janssens

- place under $WM_THIRD_PARTY_DIR/lib/$WM_OPTIONS
- relocate FOAM_MPI_LIBBIN accordingly

- solves problems that can occur when checking $PWD and links are involved

- also gives better isolation between scripts