- Claim expiration collects all players (uuids) that own claims, and
iterates this set instead of iterating through every single claim.
- Individual claims had a "last modified" timestamp, so this method was
valid before, but makes no sense now since expiration is based on player
inactivity instead of claim inactivity.
New config option under the advanced node allows controlling the
frequency each player in the aforementioned set is checked for
inactivity.
