vtkPlotPoints selections must be sorted
vtkPlotPoints selections must be sorted

Otherwise when doing unions of selections, std::union_set might complain.

Change-Id: If732768a559aad5617c75c40c787c197cced1ec2

sankhesh/VTK,gram526/VTK,jmerkow/VTK,keithroe/vtkoptix,msmolens/VTK,ashray/VTK-EVM,jmerkow/VTK,msmolens/VTK,demarle/VTK,SimVascular/VTK,sumedhasingla/VTK,keithroe/vtkoptix,mspark93/VTK,sumedhasingla/VTK,msmolens/VTK,candy7393/VTK,ashray/VTK-EVM,candy7393/VTK,hendradarwin/VTK,jmerkow/VTK,mspark93/VTK,ashray/VTK-EVM,gram526/VTK,sankhesh/VTK,hendradarwin/VTK,gram526/VTK,sumedhasingla/VTK,msmolens/VTK,jmerkow/VTK,gram526/VTK,ashray/VTK-EVM,jmerkow/VTK,gram526/VTK,jmerkow/VTK,demarle/VTK,mspark93/VTK,ashray/VTK-EVM,demarle/VTK,gram526/VTK,hendradarwin/VTK,SimVascular/VTK,demarle/VTK,sumedhasingla/VTK,ashray/VTK-EVM,msmolens/VTK,mspark93/VTK,jmerkow/VTK,mspark93/VTK,candy7393/VTK,sankhesh/VTK,candy7393/VTK,SimVascular/VTK,keithroe/vtkoptix,candy7393/VTK,demarle/VTK,SimVascular/VTK,mspark93/VTK,mspark93/VTK,keithroe/vtkoptix,gram526/VTK,ashray/VTK-EVM,demarle/VTK,sankhesh/VTK,msmolens/VTK,keithroe/vtkoptix,jmerkow/VTK,msmolens/VTK,hendradarwin/VTK,sumedhasingla/VTK,keithroe/vtkoptix,demarle/VTK,keithroe/vtkoptix,candy7393/VTK,gram526/VTK,hendradarwin/VTK,sumedhasingla/VTK,SimVascular/VTK,demarle/VTK,SimVascular/VTK,candy7393/VTK,hendradarwin/VTK,msmolens/VTK,candy7393/VTK,hendradarwin/VTK,SimVascular/VTK,sankhesh/VTK,sumedhasingla/VTK,sankhesh/VTK,keithroe/vtkoptix,SimVascular/VTK,sumedhasingla/VTK,ashray/VTK-EVM,sankhesh/VTK,mspark93/VTK,sankhesh/VTK