Fix issues in vtkOpenGLPainterDeviceAdapter::SendMaterialProperties()
Fix issues in vtkOpenGLPainterDeviceAdapter::SendMaterialProperties()

This fixes a few issues in the SendMaterialProperties() method in
the vtkOpenGLPainterDeviceAdapter class.

1. The enums for the glMaterialfv() calls were wrong when the
   data type was double.
2. Some use-cases don't need to set the specular power. Now there
   is a check for null specular_power pointer and it will only be
   set if a valid pointer is passed.

Change-Id: Ifa3e9814f87ecaec30ad3d41a9ba706469be23ca

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