fixes to PNG support
fixes to PNG support

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