- this addresses issue #843

- Always used for optional dictionary entries, since these are individual
  values, and not meant to be embedded in a larger stream of tokens.

  Methods:
     - lookupOrDefault, lookupOrAddDefault, lookupOrDefaultCompat
     - readIfPresent, readIfPresentCompat

- Handling mandatory dictionary entries is slightly more complex,
  since these may be part of larger stream of tokens, and are often
  used in a constructor context. For example,

      word modelType(dict.lookup("type"));

  Or they are used without a definite context. For example,

      dict.lookup("format") >> outputFormat;

  Newly introduced methods for mandatory dictionary entries:
     - get, getCompat
     - read, readCompat

  In a constructor or assignment context:

      word modelType(dict.get<word>("type"));
      outputFormat = dict.lookup("format");

  without copy/move (similar to readIfPresent):

      dict.read("format", outputFormat);

- resolve in favour of "inline explicit", which had marginally more
  uses and provides consistent prefixing for inline methods.

- make the purpose more explicit, and reduces some work for the
  compiler as well.

- improves backward compatibility and more naming consistency.
  Retain setMany(iter1, iter2) to avoid ambiguity with the
  PackedList::set(index, value) method.

- required for std::iterator_traits specialization, which is used by
  the std::max_element algorithm on Darwin.

- consistency with make and more succinct.

- reduce code duplication in findEtcFiles.

Basic directional refinement:
- only for coordinate aligned meshes
- only for refinementRegions
See the mesh/snappyHexMesh/aerofoilNACA0012_directionalRefinement
tutorial.

- disallow insert() of raw pointers, since a failed insertion
  (ie, entry already existed) results in an unmanaged pointer.

  Either insert using an autoPtr, or set() with raw pointers or autoPtr.

- IOobjectList::add() now takes an autoPtr instead of an object reference

- IOobjectList::remove() now returns an autoPtr instead of a raw pointer

- use refCount instead of the tmp<...>::refCount alias

- tie the MPI rules to the base compiler type *without* its version.
  Eg, linux64Gcc (which exists) instead of linux64Gcc81

- use normal instead of volumeType to decide on the sign.
  This provides a continuous field and eliminates special handling of
  GREAT in iso-surface routines.

- fix regression in isoSurfaceCell cutting that was introduced by the
  previous adjustments for distanceSurface

- input or output scaling of values to manage dissimilar unit systems
  in the structures model

- logging of communicated force, moments and updated positions.
  This allows tracking of the information exchange throughout the
  duration of the simulation and may assist in post-simulation diagnosis.

- default is now without polyhedral decomposition, since this produces
  compacter files and VTK mananges this in most instances.
  However, provide function object flag to reinstate the old behaviour.