Fabric per player spawns

Forked from Lambdacraft because he went afk.

This mod is intended to distribute mobs evenly between all players on a fabric modloaded server.

I rewired the mixins to work with 1.16.5, and then just rewrote that part of the mod as I see fit.

How it works: 

• modifies spawn logic to count chunks (and mobs in them) in a (square) radius around the player and account for chunks shared between the players
• radius to account is based on (server) render distance (like mob caps in vanilla)
• in the end each player has their own mob cap which applies to chunks around that player. (the most full one is applied in case of overlap)
• hold glistering melon in creative/spectator to see debug info

\[This means if two players are relatively close to each other\\, they can either have 70\* mobs in the area between them, or 70\* mobs each if no mobs are between them. Though, usually, it will be 70\⋅1.5\\=105 mobs, as intended by vanilla.\]\
\ default monster mobcap, can be changed\
\\ ~1 server render distance; n_chunks_loaded_by_these_playres/(SRD⋅2+1)²

Works with Proper Mobcap Modifier) (by me)