Changed ShallowCopy to pass the leaf nodes not clone them.
Changed ShallowCopy to pass the leaf nodes not clone them.

vtkCompositeData::ShallowCopy used to clone leaf nodes rather
than passing them to the output. Changed this to preserve memory.
When a composite dataset has a lot of blocks, this makes a big
difference because datasets can use quite a bit of memory.

hendradarwin/VTK,aashish24/VTK-old,mspark93/VTK,SimVascular/VTK,demarle/VTK,sumedhasingla/VTK,hendradarwin/VTK,biddisco/VTK,sankhesh/VTK,candy7393/VTK,biddisco/VTK,hendradarwin/VTK,Wuteyan/VTK,naucoin/VTKSlicerWidgets,spthaolt/VTK,daviddoria/PointGraphsPhase1,msmolens/VTK,cjh1/VTK,sumedhasingla/VTK,collects/VTK,candy7393/VTK,Wuteyan/VTK,berendkleinhaneveld/VTK,daviddoria/PointGraphsPhase1,hendradarwin/VTK,biddisco/VTK,naucoin/VTKSlicerWidgets,gram526/VTK,keithroe/vtkoptix,ashray/VTK-EVM,cjh1/VTK,aashish24/VTK-old,gram526/VTK,jeffbaumes/jeffbaumes-vtk,jmerkow/VTK,jeffbaumes/jeffbaumes-vtk,candy7393/VTK,Wuteyan/VTK,sankhesh/VTK,aashish24/VTK-old,candy7393/VTK,aashish24/VTK-old,mspark93/VTK,sankhesh/VTK,sumedhasingla/VTK,sankhesh/VTK,msmolens/VTK,hendradarwin/VTK,SimVascular/VTK,msmolens/VTK,arnaudgelas/VTK,ashray/VTK-EVM,candy7393/VTK,sumedhasingla/VTK,Wuteyan/VTK,johnkit/vtk-dev,naucoin/VTKSlicerWidgets,mspark93/VTK,ashray/VTK-EVM,arnaudgelas/VTK,jmerkow/VTK,sumedhasingla/VTK,msmolens/VTK,demarle/VTK,sumedhasingla/VTK,jeffbaumes/jeffbaumes-vtk,jmerkow/VTK,cjh1/VTK,spthaolt/VTK,spthaolt/VTK,biddisco/VTK,daviddoria/PointGraphsPhase1,keithroe/vtkoptix,demarle/VTK,jmerkow/VTK,candy7393/VTK,demarle/VTK,hendradarwin/VTK,Wuteyan/VTK,berendkleinhaneveld/VTK,gram526/VTK,candy7393/VTK,johnkit/vtk-dev,sumedhasingla/VTK,msmolens/VTK,collects/VTK,naucoin/VTKSlicerWidgets,sankhesh/VTK,msmolens/VTK,sumedhasingla/VTK,demarle/VTK,arnaudgelas/VTK,johnkit/vtk-dev,keithroe/vtkoptix,demarle/VTK,arnaudgelas/VTK,cjh1/VTK,collects/VTK,johnkit/vtk-dev,SimVascular/VTK,keithroe/vtkoptix,SimVascular/VTK,johnkit/vtk-dev,berendkleinhaneveld/VTK,keithroe/vtkoptix,spthaolt/VTK,ashray/VTK-EVM,keithroe/vtkoptix,jmerkow/VTK,ashray/VTK-EVM,mspark93/VTK,mspark93/VTK,jeffbaumes/jeffbaumes-vtk,arnaudgelas/VTK,sankhesh/VTK,SimVascular/VTK,Wuteyan/VTK,spthaolt/VTK,SimVascular/VTK,keithroe/vtkoptix,keithroe/vtkoptix,ashray/VTK-EVM,berendkleinhaneveld/VTK,berendkleinhaneveld/VTK,jmerkow/VTK,daviddoria/PointGraphsPhase1,naucoin/VTKSlicerWidgets,collects/VTK,johnkit/vtk-dev,demarle/VTK,daviddoria/PointGraphsPhase1,cjh1/VTK,SimVascular/VTK,biddisco/VTK,hendradarwin/VTK,SimVascular/VTK,berendkleinhaneveld/VTK,demarle/VTK,spthaolt/VTK,mspark93/VTK,gram526/VTK,berendkleinhaneveld/VTK,msmolens/VTK,jmerkow/VTK,sankhesh/VTK,mspark93/VTK,cjh1/VTK,daviddoria/PointGraphsPhase1,gram526/VTK,collects/VTK,biddisco/VTK,gram526/VTK,gram526/VTK,spthaolt/VTK,jeffbaumes/jeffbaumes-vtk,ashray/VTK-EVM,naucoin/VTKSlicerWidgets,ashray/VTK-EVM,aashish24/VTK-old,johnkit/vtk-dev,candy7393/VTK,jmerkow/VTK,msmolens/VTK,mspark93/VTK,Wuteyan/VTK,jeffbaumes/jeffbaumes-vtk,collects/VTK,gram526/VTK,aashish24/VTK-old,arnaudgelas/VTK,biddisco/VTK,sankhesh/VTK