Send reminders for when event date(s) is approaching

Enhancement request: It would be great to send out reminders to the meeting organiser when the first (or indeed any) of the event dates are due (24h before?), for both finalised and also un-finalised newdles. Thanks!

Start by tracing how event dates and organiser notifications are handled for both finalised and un-finalised newdles. Clarify whether reminders should be sent 24 hours before every date or only the first, then verify that the completed behaviour covers both cases.

Written by the indexing model from the issue text.