added support for scale factors "hidden" in the space directions field added a few checks for malformed NRRD files
added support for scale factors "hidden" in the space directions field
added a few checks for malformed NRRD files

git-svn-id: 353be9ac11a1e711854a13efcc2fc17d9d6b83e7@1577 c36c8488-0289-0348-9b64-b301f74bd9a7

BlueBrain/Tuvok,BlueBrain/Tuvok,BlueBrain/Tuvok