ENH: Added a regression test for vtkPolyDataSilhouette.
ENH: Added a regression test for vtkPolyDataSilhouette.

This test was derived from the Wiki exmaple:
http://vtk.org/Wiki/VTK/Examples/PolyData/Silhouette

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