adjusted self.subjreg_dir to self.options.subjreg_dir, as it is not a MAGeTbrain object attribute
added stage hints for transforming model objects to subj space
added median surface calculations, voronoi still to do; added invert transform file for bestlinreg step
added xfminvert command to subjprep script
added inverse xfm in label resampling, bringing label to subj space
trying to access model in xfm_invert in resample_label