- the Enum::readEntry() method was previously as bit sloppy with
  respect to the enumeration that it accepted. If the input was
  non-mandatory, typos would go unnoticed. Now tighten things so that
  if an enumeration is found, it must also be valid.

STYLE: remove unused/deprecated Enum::lookupOrFailsafe() method

- this was only used in a few places internally in 1712 and 1806 but
  has since then been superseded by getOrDefault() with an optional
  'failsafe' flag.

- previously deprecated and slated for removal in 2018-03

- add triSurface::subsetMesh single-parameter variant

- An identity is often useful when generating connectivity and offset
  information.

- The optional repeat value for vtk::write() allows it to also be used
  as a fill method.

- reduced clutter. Mostly only need to scan source tree.

- 00-dummy: use wmake/src/Allmake to get native (not cross-compiled)
  wmake toolchain binaries

- reverse mapping for the original point ids. This can be useful
  when searching a subset of points, but needing to store access to
  the original point index.

- move constructor.

- Allow use/not-use subset as an optional constructor argument for
  more convenient caller logic.

- don't need extra nullptr check for some cases. Less clutter.

- changed for 1906 to have a regIOobject always cleanup its
  objectRegistry entry. No need to explicitly 'release' ownership
  for this to now happen.

- doxygen formatting for MeshObject

TODO: need to revisit

 Please enter the commit message for your changes. Lines starting

A set of libraries and executables creating a workflow for performing
gradient-based optimisation loops. The main executable (adjointOptimisationFoam)
solves the flow (primal) equations, followed by the adjoint equations and,
eventually, the computation of sensitivity derivatives.

Current functionality supports the solution of the adjoint equations for
incompressible turbulent flows, including the adjoint to the Spalart-Allmaras
turbulence model and the adjoint to the nutUSpaldingWallFunction, [1], [2].

Sensitivity derivatives are computed with respect to the normal displacement of
boundary wall nodes/faces (the so-called sensitivity maps) following the
Enhanced Surface Integrals (E-SI) formulation, [3].

The software was developed by PCOpt/NTUA and FOSS GP, with contributions from

Dr. Evangelos Papoutsis-Kiachagias,
Konstantinos Gkaragounis,
Professor Kyriakos Giannakoglou,
Andy Heather

and contributions in earlier version from

Dr. Ioannis Kavvadias,
Dr. Alexandros Zymaris,
Dr. Dimitrios Papadimitriou

[1] A.S. Zymaris, D.I. Papadimitriou, K.C. Giannakoglou, and C. Othmer.
Continuous adjoint approach to the Spalart-Allmaras turbulence model for
incompressible flows. Computers & Fluids, 38(8):1528–1538, 2009.

[2] E.M. Papoutsis-Kiachagias and K.C. Giannakoglou. Continuous adjoint methods
for turbulent flows, applied to shape and topology optimization: Industrial
applications. 23(2):255–299, 2016.

[3] I.S. Kavvadias, E.M. Papoutsis-Kiachagias, and K.C. Giannakoglou. On the
proper treatment of grid sensitivities in continuous adjoint methods for shape
optimization. Journal of Computational Physics, 301:1–18, 2015.

Integration into the official OpenFOAM release by OpenCFD

- now only needed when specify compiling -m32 on a 64-bit system.

  Internally use the __SIZEOF_LONG__ compiler macro (gcc, icc, llvm)
  to define when long is actually an int32_t.

- pending resolution of cyclic dependencies