graph-store: add deep-subset scry that allows one to scry for an upper bound of ordered items by time
graph-store: add deep-subset scry that allows one to scry for an upper
bound of ordered items by time

ngzax/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,urbit/urbit,ngzax/urbit,ngzax/urbit,ngzax/urbit,urbit/urbit