Fix image load with multiple [] notation
Fix image load with multiple [] notation

Due to changing in e165a018 code relevant to the identification of appropriate axes along which to concatenate multiple input images, the order of loops when there are multiple present was erroneously reversed.

MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3