Non-NBT/MCA code cleanups

[HoldYourWaffle]

As mentioned on Discord, these are my cleanups & refactors so far that have nothing to do with NBT or MCA. The rest of my de-duplication effort depends on the discussed moving of most NBT/MCA logic to Querz/NBT, so I'll look into that next.

I'd strongly recommend reviewing this code per-commit. I've rebased, split and rewritten the commit history countless times in an effort to make everything as review-friendly (and easy to revert) as possible, so I hope there's no weird leftovers remaining... :)