Recover tests that were deprecated by commit 7d31157b.
Rather than deprecate the tests listed below, the volume renderer has been changed to the not-deprecated vtkFixedPointVolumeRayCastMapper.
Examples/Medical/Cxx/Medical4.cxx Rendering/Volume/Testing/Python/cursor3D.py Rendering/Volume/Testing/Python/gaussian3D.py Rendering/Volume/Testing/Python/VolumePickerCrop.py Rendering/Volume/Testing/Python/VolumePicker.py Rendering/Volume/Testing/Python/TestLODProp3D.py Rendering/Volume/Testing/Python/VolumeOutlineSourceClipped.py Rendering/Volume/Testing/Python/VolumeOutlineSource.py