(enh) (#1617) save metadata for mean signal-based regressors
(enh) (#1617) save metadata for mean signal-based regressors

poldracklab/fmriprep,poldracklab/preprocessing-workflow,oesteban/fmriprep,poldracklab/fmriprep,oesteban/fmriprep,poldracklab/fmriprep,oesteban/fmriprep,poldracklab/preprocessing-workflow