This option actually do not carry out any transformation but simply resample the image with isotropic voxels (useful when volumes acquired with anisotropic voxel dimensions). This is part of Flirt but this option was not available in NiPype. I was thinking we could also create a separate function Isoresampling using Flirt with apply_isoxfm?

In any case sorry for mixing up these two commits i forgot about my previous PR