functionObjects: Simplified organization and naming

src/postProcessing/functionObjects/Allwmake

src/postProcessing/functionObjects/IO/IOFunctionObjectsDoc.H

src/postProcessing/functionObjects/IO/Make/files

src/postProcessing/functionObjects/IO/Make/options

src/postProcessing/functionObjects/field/Make/files

src/postProcessing/functionObjects/field/div/IOdiv.H

src/postProcessing/functionObjects/field/div/div.C

src/postProcessing/functionObjects/field/div/div.H

...tProcessing/functionObjects/field/div/divFunctionObject.C

...tProcessing/functionObjects/field/div/divFunctionObject.H

src/postProcessing/functionObjects/field/div/divTemplates.C

...ssing/functionObjects/field/doc/fieldFunctionObjectsDoc.H

...ionObjects/field/fieldAverage/fieldAverage/fieldAverage.H

...oordinateSystemTransform/fieldCoordinateSystemTransform.H

...rocessing/functionObjects/field/fieldMinMax/fieldMinMax.H

...functionObjects/field/fieldValues/cellSource/cellSource.H

...functionObjects/field/fieldValues/faceSource/faceSource.H

...functionObjects/field/fieldValues/fieldValue/fieldValue.H

...jects/field/fieldValues/fieldValueDelta/fieldValueDelta.H

src/postProcessing/functionObjects/field/grad/IOgrad.H