Auto remove old inactive user accounts (eg. of Y16s)

[abdatta]

Situation: Currently, accounts don't get deleted even after someone leaves the hall. As a result, the final mess bill has these old users (like Y16s) as well, although with zero mess dues for them. This also unnecessarily clogs the database.

Solution: We need to write a script that will auto-delete any account that has been inactive for over 100 days. Also, at 90 days of inactivity, we should email the user with a warning mail that their account will get removed if they do not use it for booking some extras in the next 10 days.