mesh2image: Better progress information
mesh2image: Better progress information

Split progress information into two stages: The voxel-based segmentation of the surface, and the partial volume estimation for edge voxels.

Conflicts:
  src/surface/algo/mesh2image.cpp

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