Package replication handles fetching the Minute, Hour, Day and Changeset replication
and the assocated state value from Planet OSM.
For example, to fetch the current Minute replication state:
num, fullState, err := replication.CurrentMinuteState(ctx)
This is the data in http://planet.osm.org/replication/minute/state.txt updated every minute.
Once you know the change number you want, fetch the change using:
change, err := replication.Minute(ctx, num)