- use outerProduct for sumSqr() for consistency with sqr()

- for most functions the input type and return type are identical,
  but MinMax, sumMag are not.

- use forwarding tmp factory methods, auto types

- Global functions are unary or combining binary functions, which are
  defined in MinMax.H (MinMaxOps.H).

  There are also global reduction functions (gMinMax, gMinMaxMag)
  as well as supporting 'Op' classes:

  - minMaxOp, minMaxEqOp, minMaxMagOp, minMaxMagEqOp

  Since the result of the functions represents a content reduction
  into a single MinMax<T> value (a min/max pair), field operations
  returning a field simply do not make sense.

- Implemented for lists, fields, field-fields, DimensionedField,
  GeometricField (parallel reducing, with boundaries).

- Since the minMax evaluates during its operation, this makes it more
  efficient for cases where both min/max values are required since it
  avoids looping twice through the data.

  * Changed GeometricField writeMinMax accordingly.

ENH: clip as field function

- clipping provides a more efficient, single-pass operation to apply
  lower/upper limits on single or multiple values.

  Examples,

    scalarMinMax limiter(0, 1);

    limiter.clip(value)

       -> returns a const-ref to the value if within the range, or else
          returns the appropriate lower/upper limit

    limiter.inplaceClip(value)

       -> Modifies the value if necessary to be within lower/upper limit

  Function calls

    clip(value, limiter)

       -> returns a copy after applying lower/upper limit

    clip(values, limiter)

       -> returns a tmp<Field> of clipped values

GeometricField: Renamed internalField() -> primitiveField() and dimensionedInternalField() -> internalField()

These new names are more consistent and logical because:

primitiveField():
primitiveFieldRef():
    Provides low-level access to the Field<Type> (primitive field)
    without dimension or mesh-consistency checking.  This should only be
    used in the low-level functions where dimensional consistency is
    ensured by careful programming and computational efficiency is
    paramount.

internalField():
internalFieldRef():
    Provides access to the DimensionedField<Type, GeoMesh> of values on
    the internal mesh-type for which the GeometricField is defined and
    supports dimension and checking and mesh-consistency checking.

Non-const access to the internal field now obtained from a specifically
named access function consistent with the new names for non-canst access
to the boundary field boundaryFieldRef() and dimensioned internal field
dimensionedInternalFieldRef().

See also commit 22f4ad32

There is a need to specify const or non-const access to a non-const
object which is not currently possible with the "boundaryField()" access
function the const-ness of the return of which is defined by the
const-ness of the object for which it is called.  For consistency with
the latest "tmp" storage class in which non-const access is obtained
with the "ref()" function it is proposed to replace the non-const form
of "boundaryField()" with "boundaryFieldRef()".

Thanks to Mattijs Janssens for starting the process of migration to
"boundaryFieldRef()" and providing a patch for the OpenFOAM and
finiteVolume libraries.

Foam::direction is an unsigned type which makes it easier for the
compiler to pickup and report errors in the instantiation of
VectorSpaces and associated types.

in case of tmp misuse.

Simplified tmp reuse pattern in field algebra to use tmp copy and
assignment rather than the complex delayed call to 'ptr()'.

Removed support for unused non-const 'REF' storage of non-tmp objects due to C++
limitation in constructor overloading: if both tmp(T&) and tmp(const T&)
constructors are provided resolution is ambiguous.

The turbulence libraries have been upgraded and '-DCONST_TMP' option
specified in the 'options' file to switch to the new 'tmp' behavior.

This resolves a whole range of issues and work-arounds with earlier
releases.  This version of icpc is more or less compatible with the
latest gcc and clang compilers and only required one hack to avoid
warnings from PackedBoolList.H.

This reverts commit c5bea524.

This reverts commit b18f6cc1.