- encapsulates toggling

STYLE: noexcept for some Time methods

ENH: added scalarField hypot() function

- use file-local function to reduce some code clutter

STYLE: use standard dimensionedSets

- 'unfriend' operators on dimensionSet, since they operate without
  requiring access to non-public members.

- add missing invTransform() function for dimensionSet.

- make inv(const dimensionSet&) available as
  operator~(const dimensionSet&), which can be used instead
  of (dimless/ds).

- deprecate dimensionedType constructors using an Istream in favour of
  versions accepting a keyword and a dictionary.

  Dictionary entries are almost the exclusive means of read
  constructing a dimensionedType. By construct from the dictionary
  entry instead of doing a lookup() first, we can detect possible
  input errors such as too many tokens as a result of a input syntax
  error.

  Constructing a dimensionedType from a dictionary entry now has
  two forms.

  1.  dimensionedType(key, dims, dict);

      This is the constructor that will normally be used.

      It accepts entries with optional leading names and/or
      dimensions. If the entry contains dimensions, they are
      verified against the expected dimensions and an IOError is
      raised if they do not correspond. On conclusion, checks the
      token stream for any trailing rubbish.

  2.  dimensionedType(key, dict);

      This constructor is used less frequently.

      Similar to the previous description, except that it is initially
      dimensionless. If entry contains dimensions, they are used
      without further verification. The constructor also includes a
      token stream check.

      This constructor is useful when the dimensions are entirely
      defined from the dictionary input, but also when handling
      transition code where the input dimensions are not obvious from
      the source.

      This constructor can also be handy when obtaining values from
      a dictionary without needing to worry about the input dimensions.
      For example,

         Info<< "rho: " << dimensionedScalar("rho", dict).value() << nl;

      This will accept a large range of inputs without hassle.

ENH: consistent handling of dimensionedType for inputs (#1083)

BUG: incorrect Omega dimensions (fixes #2084)

- when constructing dimensioned fields that are to be zero-initialized,
  it is preferrable to use a form such as

      dimensionedScalar(dims, Zero)
      dimensionedVector(dims, Zero)

  rather than

      dimensionedScalar("0", dims, 0)
      dimensionedVector("zero", dims, vector::zero)

  This reduces clutter and also avoids any suggestion that the name of
  the dimensioned quantity has any influence on the field's name.

  An even shorter version is possible. Eg,

      dimensionedScalar(dims)

  but reduces the clarity of meaning.

- NB: UniformDimensionedField is an exception to these style changes
  since it does use the name of the dimensioned type (instead of the
  regIOobject).

- makes it easier to transmit or stream as a list of scalars

Henry Weller authored 7 years ago and Andrew Heather committed 7 years ago

"pos" now returns 1 if the argument is greater than 0, otherwise it returns 0.
This is consistent with the common mathematical definition of the "pos" function:

https://en.wikipedia.org/wiki/Sign_(mathematics)

However the previous implementation in which 1 was also returned for a 0
argument is useful in many situations so the "pos0" has been added which returns
1 if the argument is greater or equal to 0.  Additionally the "neg0" has been
added which returns 1 if if the argument is less than or equal to 0.

posPart returns a value or field in which the value or values are set to
0 if negative

negPart returns a value or field in which the value or values are set to
0 if positive

This reverts commit c5bea524.

This reverts commit b18f6cc1.

- added asText() method to assist people with remembering what the
  dimensions are in English

- minor short-circuit optimizations in dimensionless() and operator==

 - graham showed significant speedup (8-9x) for sqrt(sqrt(x)) compared to pow(x, 0.25)