Escalate lessons emails based on number of emails sent instead of date

Currently, the system uses the date difference between when a lesson was due and the current date to determine which type of email to send and who to send it to. Immediately after a school holiday period, this can be an issue as emails get escalated before the prior emails have been sent.

Instead, implement a counter on the roll that tracks how many emails have been sent about this roll previously, and then use that to escalate the email. This will ensure that the first email to be sent about an overdue lesson does not get incorrectly escalated to the Principal of the school.

ulnagar / Constellation

Escalate lessons emails based on number of emails sent instead of date #25