Activity tracking
Track the last read marker and last sent message per user and room (cf. AlekSIS-Core#733).
We would use this at Teckids for a reminder system, that makes it visible to users (and the pedagogic team) when a person had their last activities in systems connected to AlekSIS.
Technically, we could probably track the last activity per event type, and depending on which route we choose in the linked issue in core, we might consider just asking Matrix for that information if someone ask for it through the API (though I am not a fan of this because it is not database-off-loadable).