instead of removing them. Now done similar to 23x:
- in 'removing unreachable parts of mesh' keep regions unset (so they get removed)
- in final zoning set to background region

See Gitlab #66.

Feature iotweaks

Enhancements for #114 and #115. Tagged as WIP, since there may be some need for discussion/rework prior to merging.

See merge request !35

Merge foundation

Integrating latest code from the OF Foundation - main changes:

Lots of renaming/refactoring:
- to retrieve reference from tmp, now need to use tmp.ref() as opposed to tmp()
- fvc::flux function to replace fvc::interpolate(<field>) & mesh.Sf()
- integration of new c++ features: no more spaces between closing template braces, e.g. class1<class2<Type> > becomes class1<class2<Type>>
- DataEntry renamed to Function1

New functionality:
- Updated 6DoF
- fvOptions support in turbulence models

See merge request !33

ENH: added -decomposeParDict as argument to getNumberOfProcessors()

Continuing discussion at 
https://develop.openfoam.com/Development/OpenFOAM-plus/commit/1507178a1bfffef916faab8f6d69dd72c3f0ee76?title=#note_1093

Now the Allrun script could be
```
runParallel -decomposeParDict system/decomposeParDict-6 snappyHexMesh -overwrite
```

Thanks @Mattijs 


See merge request !36

Revert "Change boundaryRadiationProperties and boundaryRadiationPropertiesPatch to mesh object and changing tutorials accordingly"

This reverts commit 662f9242.

Note: functionality moved to feature-boundaryRadiationProperties branch

Merge branch 'merge-foundation' of develop.openfoam.com:Development/OpenFOAM-plus into merge-foundation

Change boundaryRadiationProperties and boundaryRadiationPropertiesPatch to mesh object and changing tutorials accordingly

Merge branch 'merge-foundation' of develop.openfoam.com:Development/OpenFOAM-plus into merge-foundation

BUG: boundaryRadiationProperties - updated to use caseConstant() for parallel usage and updated style

Merge branch 'merge-foundation' of develop.openfoam.com:Development/OpenFOAM-plus into merge-foundation

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=2062

Resolves bug-report http://openfoam.org/mantisbt/view.php?id=2061

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=2060

Now the calculation of the 2nd-invariant is more efficient and
accumulates less round-off error.