BUG: Fix closed vtkKochanekSpline derivatives at first/last point.
BUG: Fix closed vtkKochanekSpline derivatives at first/last point.

The scaling parameters for nonuniform sampling were miscomputed for
the first/last point in closed curves.  Also, the code for generating
a straight line segment for data with just two points was both
unnecessary and incorrect, it ignored the possibility of end-point
derivatives generating a curve from just the two points.

Change-Id: I5229b839d6d70ba5c44a0fbea45b82ea050d6327

demarle/VTK,hendradarwin/VTK,candy7393/VTK,jmerkow/VTK,jmerkow/VTK,sumedhasingla/VTK,ashray/VTK-EVM,biddisco/VTK,collects/VTK,candy7393/VTK,sankhesh/VTK,keithroe/vtkoptix,ashray/VTK-EVM,msmolens/VTK,jmerkow/VTK,SimVascular/VTK,gram526/VTK,keithroe/vtkoptix,keithroe/vtkoptix,aashish24/VTK-old,cjh1/VTK,ashray/VTK-EVM,ashray/VTK-EVM,biddisco/VTK,keithroe/vtkoptix,collects/VTK,hendradarwin/VTK,SimVascular/VTK,aashish24/VTK-old,demarle/VTK,sankhesh/VTK,sankhesh/VTK,ashray/VTK-EVM,johnkit/vtk-dev,SimVascular/VTK,spthaolt/VTK,candy7393/VTK,berendkleinhaneveld/VTK,gram526/VTK,ashray/VTK-EVM,biddisco/VTK,cjh1/VTK,sumedhasingla/VTK,gram526/VTK,jmerkow/VTK,SimVascular/VTK,ashray/VTK-EVM,hendradarwin/VTK,gram526/VTK,mspark93/VTK,jmerkow/VTK,demarle/VTK,demarle/VTK,sumedhasingla/VTK,sumedhasingla/VTK,hendradarwin/VTK,sumedhasingla/VTK,SimVascular/VTK,keithroe/vtkoptix,mspark93/VTK,mspark93/VTK,aashish24/VTK-old,berendkleinhaneveld/VTK,candy7393/VTK,biddisco/VTK,hendradarwin/VTK,mspark93/VTK,aashish24/VTK-old,mspark93/VTK,collects/VTK,jmerkow/VTK,spthaolt/VTK,biddisco/VTK,SimVascular/VTK,biddisco/VTK,cjh1/VTK,candy7393/VTK,sankhesh/VTK,collects/VTK,collects/VTK,berendkleinhaneveld/VTK,berendkleinhaneveld/VTK,aashish24/VTK-old,msmolens/VTK,johnkit/vtk-dev,msmolens/VTK,cjh1/VTK,keithroe/vtkoptix,SimVascular/VTK,johnkit/vtk-dev,berendkleinhaneveld/VTK,johnkit/vtk-dev,berendkleinhaneveld/VTK,aashish24/VTK-old,msmolens/VTK,sumedhasingla/VTK,gram526/VTK,jmerkow/VTK,spthaolt/VTK,spthaolt/VTK,sankhesh/VTK,SimVascular/VTK,msmolens/VTK,gram526/VTK,candy7393/VTK,spthaolt/VTK,demarle/VTK,sankhesh/VTK,gram526/VTK,biddisco/VTK,ashray/VTK-EVM,cjh1/VTK,msmolens/VTK,gram526/VTK,spthaolt/VTK,spthaolt/VTK,mspark93/VTK,hendradarwin/VTK,johnkit/vtk-dev,mspark93/VTK,sumedhasingla/VTK,sankhesh/VTK,johnkit/vtk-dev,sumedhasingla/VTK,msmolens/VTK,keithroe/vtkoptix,sankhesh/VTK,demarle/VTK,berendkleinhaneveld/VTK,keithroe/vtkoptix,johnkit/vtk-dev,candy7393/VTK,demarle/VTK,msmolens/VTK,jmerkow/VTK,candy7393/VTK,mspark93/VTK,demarle/VTK,cjh1/VTK,collects/VTK,hendradarwin/VTK