ADD: Added classes for label object representation and manipulation

...s/InsightJournal/itkAttributeKeepNObjectsLabelMapFilter.h

...InsightJournal/itkAttributeKeepNObjectsLabelMapFilter.txx

Utilities/InsightJournal/itkAttributeLabelObject.h

Utilities/InsightJournal/itkAttributeOpeningLabelMapFilter.h

...ties/InsightJournal/itkAttributeOpeningLabelMapFilter.txx

Utilities/InsightJournal/itkAttributeRelabelImageFilter.h

Utilities/InsightJournal/itkAttributeRelabelImageFilter.txx

Utilities/InsightJournal/itkAttributeRelabelLabelMapFilter.h

...ties/InsightJournal/itkAttributeRelabelLabelMapFilter.txx

...ties/InsightJournal/itkAttributeSelectionLabelMapFilter.h

...es/InsightJournal/itkAttributeSelectionLabelMapFilter.txx

Utilities/InsightJournal/itkAutoCropLabelMapFilter.h

Utilities/InsightJournal/itkAutoCropLabelMapFilter.txx

...nsightJournal/itkBinaryAttributeKeepNObjectsImageFilter.h

...ightJournal/itkBinaryAttributeKeepNObjectsImageFilter.txx

...ies/InsightJournal/itkBinaryAttributeOpeningImageFilter.h

...s/InsightJournal/itkBinaryAttributeOpeningImageFilter.txx

...ightJournal/itkBinaryClosingByReconstructionImageFilter.h

...htJournal/itkBinaryClosingByReconstructionImageFilter.txx

Utilities/InsightJournal/itkBinaryFillholeImageFilter.h