- in many cases can just use lookupOrDefault("key", bool) instead of
  lookupOrDefault<bool> or lookupOrDefault<Switch> since reading a
  bool from an Istream uses the Switch(Istream&) anyhow

STYLE: relocated Switch string names into file-local scope

- sentinel was not working properly when building user-space routines

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;

- Can occur if the selected geometry does not actually exist.
  A non-critical bug since paraview catches this anyhow and
  just emits a warning message.

- previous only checked for clouds at the last instance and only
  detected lagrangian fields from the first cloud.

  Now check for clouds at all instances and detect all of their fields
  as well.

- use allocator class to wrap the stream pointers instead of passing
  them into ISstream, OSstream and using a dynamic cast to delete
  then. This is especially important if we will have a bidirectional
  stream (can't delete twice!).

STYLE:

- file stream constructors with std::string (C++11)

- for rewind, explicit about in|out direction. This is not currently
  important, but avoids surprises with any future bidirectional access.

- combined string streams in StringStream.H header.
  Similar to <sstream> include that has both input and output string
  streams.

- elminate the foamVtkFormatter operator() in favour of xmlAttr.
  Improves readability and the purpose is clearer.

- The reader module allows two levels of caching.
  The OpenFOAM fvMesh can be cached in memory, for faster loading of
  fields. Additionally, the translated VTK geometries are held in a
  local cache. The cached VTK geometries should incur no additional
  overhead since they use the VTK reference counting for their storage
  management.

ENH: Paraview modules.

- Update props with int, not bool (for more versatility)
- Set properties and tool-tips directly on widgets instead of buttons

- this allows filling in the VTK structures without intermediate data
  and without sequencial insertion. Should be faster and smaller
  than the previous cell-wise insertion methods.
  Most importantly, it improves code reuse.

- this greatly simplifies data management and opens the possibility of
  reusing converted vtk meshes instead of converting each time.

- has the selected values directly and use these lookup names to store
  directly into a hash. This replaces several parallel lists of
  decomp information etc and makes it easier.

- improves the overview of the code

- avoids potentially issues if we reusing a vtkPoints array,
  and should be marginally faster without the additional
  range checking.

- adds flexiblity and reduces risk of memory leaks as we add/change
  features

STYLE: adjust naming for paraview internal polyDecomp

- easier to detect the implicit grouping

- also use updated forAll* macros

COMP: avoid undefined-var-template warning in runTimePostProcessing

- simplifies organization, includes, linkage etc.

- less clutter and typing to use the default template parameter when
  the key is 'word' anyhow.

- use EdgeMap instead of the longhand HashTable version where
  appropriate

- they don't use scotch/metis anyhow, which are the only things
  placed in FOAM_EXT_LIBBIN

- can be used directly from within an application or function-object.
  Makes it available for dictionaries.

STYLE: improve consistency in Allwclean scripts

- reduces unexpected interactions between various make elements