STYLE: CoordRepType -> CoordinateType code readability

For the sake of code readability, a new 'CoordinateType' alias is added for
each nested 'CoordRepType' alias. The old 'CoordRepType' aliases will still be
available with ITK 6.0, but it is recommended to use 'CoordinateType' instead.
The 'CoordRepType' aliases will be removed when 'ITK_FUTURE_LEGACY_REMOVE' is
enabled. Similarly, 'InputCoordinateType', 'OutputCoordinateType', and
'ImagePointCoordinateType' replace 'InputCoordRepType', 'OutputCoordRepType',
and 'ImagePointCoordRepType', respectively.

Author: hjmjohnson

include/itkPolyData.h

@@ -57,7 +57,7 @@ class ITK_TEMPLATE_EXPORT PolyData: public DataObject
   using MeshTraits = DefaultStaticMeshTraits< PixelType, PointDimension, PointDimension, float, float, CellPixelType >;
 
   /** Convenient type alias obtained from TMeshTraits template parameter. */
-  using CoordRepType = typename MeshTraits::CoordRepType;
+  using CoordinateType = typename MeshTraits::CoordinateType;
   using PointIdentifier = typename MeshTraits::PointIdentifier;
   using PointType = typename MeshTraits::PointType;
   using PointsContainer = typename MeshTraits::PointsContainer;

include/itkPolyDataToMeshFilter.h

@@ -60,7 +60,7 @@ class PolyDataToMeshFilter : public ProcessObject
   using OutputMeshType = Mesh<typename InputPolyDataType::PixelType, PointDimension>;
   using MeshType = OutputMeshType;
 
-  using OutputCoordRepType = typename OutputMeshType::CoordRepType;
+  using OutputCoordinateType = typename OutputMeshType::CoordinateType;
   using OutputPointPixelType = typename OutputMeshType::PixelType;
   using OutputCellPixelType = typename OutputMeshType::CellPixelType;
   using OutputPointType = typename OutputMeshType::PointType;