BUG: 2466, MRMLIDImageIO crashes with DWMRI volume
http://www.na-mic.org/Bug/view.php?id=2466
Restore handling of b-values and gradients, and make code consistent
with DWIConvert: use the sqrt(b/b_max)
scaling factor as documented
on the NA-MIC wiki page:
http://wiki.na-mic.org/Wiki/index.php/NAMIC_Wiki:DTI:Nrrd_format