NRRD file support

Reposted from discourse:

The NRRD format specification requires that extra whitespace after the field descriptor and before the line termination is ignored. However, the function ParseVector vtkNrrdReader.cxx trims the input string, but does not ignore white space within a string.

Therefore, Paraview will parse the vectors:

space directions: (2.9356703758239746,0,0) (0,2.949852466583252,0) (0,0,2.9361956119537354)
space origin: (-75.762535095214844,-110.76253509521484,-71.762535095214844)

But fail to parse the vectors:

space directions: (2.9356703758239746, 0, 0) (0, 2.949852466583252, 0) (0, 0, 2.9361956119537354)
space origin: (-75.762535095214844, -110.76253509521484, -71.762535095214844)

The user is provided with no feedback regarding an error, but no image is displayed. Careful inspection of the image properties will reveal that the spatial "Bounds" all have a delta of zero (e.g. all voxels collapsed to single point).

Here is a small example illustrating this issue.