Dark Swarm

1. New feature: the datapack difficulty scales with "approximate player level". The goal is to make it slightly easier early game:

• Overall change: early game=easier, late game=unchanged
• The "approximate player level" is calculated using number of Dark Nights player has lived through and whether they have some major advancements
• The mobs' hp and damage for early game is now 75% of what it used to be before this patch and scales to 100% with "approximate player level"
• The spawn rates are also lower during early game - Darkness mobs spawn slightly slower for new players

 How the formula roughly works:

• player in new world who doesn't even have iron armor = treated as "low level"
• player who lived one night, has iron armor = "mid level"
• player who lived through few nights and has diamond armor already = treated as "high level"

2. More performance improvements. Using more dx/dy/dz and world selectors to prevent scanning all entities
3. Phantoms are now being insta-killed during Dark Night (they're annoying and actually impossible to prevent from spawning if sleep is disabled + everyday night frequency)