changed gzopen64 / gzseek64 / gztell64 calls to the standard gzopen / gzseek / gztell calls, since these aren't available by default on all systems, and are equivalent on 64-bit systems anyway
changed gzopen64 / gzseek64 / gztell64 calls to the standard gzopen / gzseek / gztell calls, since these aren't available by default on all systems, and are equivalent on 64-bit systems anyway

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