- for some special cases we wish to mark command-line arguments as
  being optional, in order to do our own treatment. For example,
  when an arbitrary number of arguments should be allowed.

  Now tag this situation with argList::noMandatoryArgs().
  The argList::argsMandatory() query can then be used in any further
  logic, including the standard default argument checking.

- with the new default check, can consolidate the special-purpose

      "setRootCaseNonMandatoryArgs.H"

  into the regular

      "setRootCase.H"

- revert to a simple "setRootCase.H" and move all the listing related
  bits to a "setRootCaseLists.H" file. This leaves the information
  available for solvers, or whoever else wishes, without being
  introduced everywhere.

- add include guards and scoping to the listing files and rename to
  something less generic.

     listOptions.H -> setRootCaseListOptions.H
     listOutput.H  -> setRootCaseListOutput.H

- controlled by the the 'printExecutionFormat' InfoSwitch in
  etc/controlDict

      // Style for "ExecutionTime = " output
      // - 0 = seconds (with trailing 's')
      // - 1 = day-hh:mm:ss

   ExecutionTime = 112135.2 s  ClockTime = 113017 s

   ExecutionTime = 1-07:08:55.20  ClockTime = 1-07:23:37

- Callable via the new Time::printExecutionTime() method,
  which also helps to reduce clutter in the applications.
  Eg,

     runTime.printExecutionTime(Info);

  vs

     Info<< "ExecutionTime = " << runTime.elapsedCpuTime() << " s"
         << "  ClockTime = " << runTime.elapsedClockTime() << " s"
         << nl << endl;

--

ENH: return elapsedClockTime() and clockTimeIncrement as double

- previously returned as time_t, which is less portable.

e.g. (fvc::interpolate(HbyA) & mesh.Sf()) -> fvc::flux(HbyA)

This removes the need to create an intermediate face-vector field when
computing fluxes which is more efficient, reduces the peak storage and
improved cache coherency in addition to providing a simpler and cleaner
API.

The boundary conditions of HbyA are now constrained by the new "constrainHbyA"
function which applies the velocity boundary values for patches for which the
velocity cannot be modified by assignment and pressure extrapolation is
not specified via the new
"fixedFluxExtrapolatedPressureFvPatchScalarField".

The new function "constrainPressure" sets the pressure gradient
appropriately for "fixedFluxPressureFvPatchScalarField" and
"fixedFluxExtrapolatedPressureFvPatchScalarField" boundary conditions to
ensure the evaluated flux corresponds to the known velocity values at
the boundary.

The "fixedFluxPressureFvPatchScalarField" boundary condition operates
exactly as before, ensuring the correct flux at fixed-flux boundaries by
compensating for the body forces (gravity in particular) with the
pressure gradient.

The new "fixedFluxExtrapolatedPressureFvPatchScalarField" boundary
condition may be used for cases with or without body-forces to set the
pressure gradient to compensate not only for the body-force but also the
extrapolated "HbyA" which provides a second-order boundary condition for
pressure.  This is useful for a range a problems including impinging
flow, extrapolated inlet conditions with body-forces or for highly
viscous flows, pressure-induced separation etc.  To test this boundary
condition at walls in the motorBike tutorial case set

    lowerWall
    {
        type            fixedFluxExtrapolatedPressure;
    }

    motorBikeGroup
    {
        type            fixedFluxExtrapolatedPressure;
    }

Currently the new extrapolated pressure boundary condition is supported
for all incompressible and sub-sonic compressible solvers except those
providing implicit and tensorial porosity support.  The approach will be
extended to cover these solvers and options in the future.

Note: the extrapolated pressure boundary condition is experimental and
requires further testing to assess the range of applicability,
stability, accuracy etc.

Henry G. Weller
CFD Direct Ltd.

For DyM solvers phiAbs is replaced by Uf but this conversion is currently not complete

This reverts commit c5bea524.

This reverts commit b18f6cc1.

Exception: applyWallFunctionBoundaryConditions.C cannot split #include
directives.

- change system/controlDict to use functions {..} instead of functions (..);
  * This is internally more efficient
- fixed formatting of system/controlDict functions entry

- pedantic change: use 'return 0' instead of 'return(0)' in the applications,
  since return is a C/C++ keyword, not a function.

- this (now deprecated) idiom:
      for (runTime++; !runTime.end(); runTime++) { ... }
  has a few problems:
    * stop-on-next-write will be off-by-one (ie, doesn't work)
    * function objects are not executed on exit with runTime.end()
  Fixing these problems is not really possible.

- this idiom
      while (runTime.run())
      {
          runTime++;
          ...
      }
  works without the above problems.