replace itkstaticconstmacro with constexpr#36

hjmjohnson merged 8 commits intomainInsightSoftwareConsortium/ITKBSplineGradient:mainfrom

replace-itkstaticconstmacro-with-constexprInsightSoftwareConsortium/ITKBSplineGradient:replace-itkstaticconstmacro-with-constexprCopy head branch name to clipboard