Fixed a bug where Mythic Mobs were either being removed when they shouldn't or weren't being removed when they should
The timer intervals are now per-world instead of on a global level, meaning one world can remove entities every 5 minutes whereas another world can be set to 15 minutes
The countdown-on-command option was removed due to the complexity of this new system and will now default to skipping the countdowns
It's possible I missed something in testing, so please submit an issue on GitHub if you come across any bugs