timeVaryingMappedFixedValue: Reinstated support for AverageField

...fields/pointPatchFields/pointPatchField/pointPatchField.C

...fields/pointPatchFields/pointPatchField/pointPatchField.H

...enFOAM/primitives/functions/Function1/Constant/Constant.C

...enFOAM/primitives/functions/Function1/Constant/Constant.H

src/finiteVolume/Make/files

...Fields/derived/timeVaryingMappedFixedValue/AverageField.C

...Fields/derived/timeVaryingMappedFixedValue/AverageField.H

...lds/derived/timeVaryingMappedFixedValue/AverageIOFields.C

...appedFixedValue/timeVaryingMappedFixedValueFvPatchField.C

...appedFixedValue/timeVaryingMappedFixedValueFvPatchField.H

...edFixedValue/timeVaryingMappedFixedValuePointPatchField.C

...edFixedValue/timeVaryingMappedFixedValuePointPatchField.H

.../sampledSurface/sampledCuttingPlane/sampledCuttingPlane.H

src/sampling/sampledSurface/sampledPlane/sampledPlane.H