rename slice to region
rename slice to region

dwhswenson/openpathsampling,openpathsampling/openpathsampling,dwhswenson/openpathsampling,choderalab/openpathsampling,dwhswenson/openpathsampling,openpathsampling/openpathsampling,jhprinz/openpathsampling,choderalab/openpathsampling,dwhswenson/openpathsampling,openpathsampling/openpathsampling,jhprinz/openpathsampling,choderalab/openpathsampling,jhprinz/openpathsampling,openpathsampling/openpathsampling