message: COMP: backward compatibility with ITK v4.12
diff: #include "rtkMacro.h"
  #include "itkMetaProgrammingLibrary.h"
  -#include <itkMultiplyImageFilter.h>
  #include <itkEnableIf.h>
  +#if ITK_VERSION_MAJOR<5
  +# include <itkBinaryFunctorImageFilter.h>
  +#else
  +# include <itkBinaryGeneratorImageFilter.h>
  +#endif
  namespace rtk
  {
  @@ -76,12 +80,20 @@ namespace Functor
  template< typename TImage >
  class ITK_EXPORT DotProductImageFilter:
  public
  +#if ITK_VERSION_MAJOR<5
  + itk::BinaryFunctorImageFilter< TImage, TImage, TImage, typename Functor::DotProduct<TImage, double> >
  +#else
  itk::BinaryGeneratorImageFilter< TImage, TImage, typename itk::Image<typename TImage::InternalPixelType, TImage::ImageDimension> >
  +#endif
  {
  public:
  /** Standard class typedefs. */
  typedef DotProductImageFilter Self;
  +#if ITK_VERSION_MAJOR<5
  + typedef itk::BinaryFunctorImageFilter< TImage, TImage, TImage, typename Functor::DotProduct<TImage, double> > Superclass;
  +#else
  typedef itk::BinaryGeneratorImageFilter< TImage, TImage, typename itk::Image<typename TImage::InternalPixelType, TImage::ImageDimension> > Superclass;
  +#endif
  typedef itk::SmartPointer< Self > Pointer;
  typedef itk::SmartPointer< const Self > ConstPointer;
  @@ -93,7 +105,11 @@ public:
  /** Runtime information support. */
  itkTypeMacro(DotProductImageFilter,
  +#if ITK_VERSION_MAJOR<5
  + itk::BinaryFunctorImageFilter);
  +#else
  itk::BinaryGeneratorImageFilter);
  +#endif
  protected:
  DotProductImageFilter()
  