FIX: Remove all vtkgl dependencies for vtkRenderingVolumeOpenGLNew

Change-Id: I02b65ea5cd10e8e10df0408a45f7c3eb2a1344ed
Merge topic 'remove_vtkgl_dependency' into master

9e57befb FIX: Remove all vtkgl dependencies for vtkRenderingVolumeOpenGLNew