--inputBVectors input parsing improved

I found the parsing was in a different order than *.bvec generated by dcm2nii. I have modified the parser to work with either scheme. 

ie either
x1 y1 z1
x2 y2 z2
x3 y3 z3
x4 y4 z4

or 

x1 x2 x3 x4
y1 y2 y3 y4
z1 z2 z3 z4

now works. This means that taking output from dcm2nii will now work (in the rare case where dicom parsing works better in dcm2nii). I also ensure that the input is actually Nx3 or 3xN.