Monitor continuously

[ModischFabrications]

Keep polling the server even when noone is asking.

• "online for 6 hours"
• "no one played for an hour, stopping..."

[ModischFabrications]

This can be merged with the scheduler.

Using a flag to turn this feature off is neat, but probably useless as this will consume very little resources either way.

Implementation idea:

1. Start thread and poll server with underlying _observer every 30s, similar to scheduler
2. log timestamp and type of each server change (state, players)
3. turn off server after MAX_SERVER_IDLE_S
4. purge old log entries or offer log via command?