OPT: update the script isct_get_fractional_volume that also uses the function read_label_file
OPT: update the script isct_get_fractional_volume that also uses the function read_label_file

3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox