add storage for RETISTransition
add storage for RETISTransition

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