MRView: fix bug in 'colour by track ends' in alternate tractography tool implementation
MRView: fix bug in 'colour by track ends' in alternate tractography tool implementation

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