move t1 overlay image creation into the t1 workflow
move t1 overlay image creation into the t1 workflow

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