Experimenting with TravisCI changes
Experimenting with TravisCI changes

Try to construct a build matrix where each job only runs a subset of the required tests.

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