mrtransform: fix rotation of directions header entries if replace and not DW gradient information present
mrtransform: fix rotation of directions header entries if replace and not DW gradient information present

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