comments

- added (cumulative) contributions due to transfer of mass, mom and energy when
  evaluating cell properties

Conflicts:
	src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/nutWallFunctions/nutRoughWallFunction/nutRoughWallFunctionFvPatchScalarField.C

Conflicts:
	src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/nutWallFunctions/nutRoughWallFunction/nutRoughWallFunctionFvPatchScalarField.C

location for the specification is the same as that for the pd level.

- with minor additional changes

- explicitly remove any previously decomposed 'mut' and 'nut' when
  decomposing fields since they can otherwise prevent the turbulence model
  from being upgraded properly.
  Removing all decomposed fields first might be a better idea in the
  long-term, but would probably be slower.

- added constructor dictionary(const dictionary*) that also handles NULL
  pointers and makes it convenient to construct from a possibly nonexistent
  sub-dictionary:
  eg,
      dictionary dict2(dict1.subDictPtr("someDict"));

- make some of the turbulence Coeffs sub-dictionary optional.
  Their contents are all 'lookupOrAddDefault' anyhow.

- in turbulentMixingLength BCs, skip namespace qualifier in template
  (eg, <RASModel> vs. <compressible::RASModel>)

- change comments from 'turbulenceProperties' to RASProperties/LESProperties

- consistency between compressible/incompressible - no separate file for
  'New' selector etc

- consistency in accessing the model coefficients.
  Use method coeffDict() for const access.
  Use protected data member coeffDict_ for read/write access.

- document model coefficients in etc/constant/RASProperties.
  Need the same for LESProperties before we can prune these from the
  tutorials.