Port to 1.20.1 and support block entities

[ThatCreeper]

I probably shouldn't have made both in a single pull request but hey.

The way I'm supporting block entities appears to work and hasn't given me any issues so far, but it could probably be made more memory efficient in at least some way.

There shouldn't be any issues that are too bad in this, seeing as I've been using it for a little bit and it seems to be working.

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The 1.20.1 version of this is only very lightly tested, but it appears to work fine?

If anyone finds something wrong with this, feel free to put a comment either here or on my fork's issues page!

[Guerdi]

You are the best❤️

[popos123]

It is possible to get .jar build file for the 1.20.1?

[ThatCreeper]

You should be able to find a build on Modrinth under "Immersive Cursedness Updated"

[ExplosiveGeek77]

1.20.6????