Implemented an IndexingMode iVar and convenience methods
Implemented an IndexingMode iVar and convenience methods

Change-Id: I479a708b60328c802578541d4386a0776785a1c2

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