- This class is largely a pre-C++11 holdover, prior to having movable
  references.

- align internals with autoPtr instead of always unconditionally
  allocating memory. The valid() method can be used to check for a null
  pointer.

- Consolidate into a single file, in anticipation of future removal.

- rvalue() is a (transitional) means of converting Xfer content to a
  reference for move construct, move assign semantics.

- valid() method for consistency with autoPtr and tmp classes

STYLE: simplified output logic, reduced duplicate code in CompactIOList

- now also handles negative indices without issue.
  This increases its robustness for predicate type of use.

several improvements for linked-lists

See merge request OpenFOAM-plus!177

- deprecated MAR-2017

    subset(const UList<T>& select, const T& value, const ListType&);
    inplaceSubset(const UList<T>& select, const T& value, ListType&);

  The subsetList/inplaceSubsetList variants with a unary predicate
  provide more flexible and robuster solutions.

- deprecated MAR-2017

    initList(const T[mRows]);
    initListList(const T[mRows][nColumns]);

  Required prior to the addition of constructors with
  std::initializer_list

- the wordHashSet typedef is always available when HashSet has been
  included.

- use default HashTable key (word) instead of explicitly mentioning it

* For most cases, this conversion would be largely unintentional
  and also less efficient. If the regex is desirable, the caller
  should invoke it explicitly.
  For example,

      findStrings(regExp(str), listOfStrings);

  Or use one of the keyType, wordRe, wordRes variants instead.
  If string is to be used as a plain (non-regex) matcher,
  this can be directly invoked

      findMatchingStrings(str, listOfStrings);

  or using the ListOps instead:

      findIndices(listOfStrings, str);

* provide function interfaces for keyType.

- subsetList, inplaceSubsetList with optional inverted logic.

- use moveable elements where possible.

- allow optional starting offset for the identity global function.
  Eg,  'identity(10, start)' vs 'identity(10) + start'

- this permits direct storage of a list with additional matcher
  capabilities

- provide wordRes::matcher class for similar behaviour as previously

Eg, -entry boundaryField/wall2/q  vs. boundaryField.wall2.q

- remove unneeded quoting when calling foamDictionary

- now replaced 'if ! isTest' with 'if notTest' for most cases.

- should have been limited to non-processor patches only

- returns the number of non-processorPolyPatch patches, which is invariant
  across all processors.

- remove writeLagrangianCoordinates as InfoSwitch, since this is
  something that a regular user should not be able to disable.

- more consistent with STL practices for function classes.

- string::hash function class now operates on std::string rather
  than Foam::string since we have now avoided inadvertent use of
  string conversion from int in more places.

- Eg instead of using labelHashSet, used HashSet<label> which uses
  the string::hash for hashing. Other places inadvertently using the
  string::hash instead of Hash<label> for hashing.

STYLE: use Map<..> instead of HashTable<.., label, Hash<label>>

- reduces clutter

- reduces some ambiguity and clarifies the expected output and
  behaviour.

STYLE: reduce some automatic conversions of char to string

- avoid confusion by using HashTable::lookup(key, deflt) explicitly
  instead of allowing an operator() version.

- add copy construct from UList

- remove copy construct from dissimilar types.

  This templated constructor was too generous in what it accepted.
  For the special cases where a copy constructor is required with
  a change in the data type, now use the createList factory method,
  which accepts a unary operator. Eg,

      auto scalars = scalarList::createList
      (
          labels,
          [](const label& val){ return 1.5*val; }
      );