WIP: initial work on reworked regeneration logic

[PierreSchwang]

Reworked regeneration logic to be faster (kinda). And does not use reflection anymore - yay.

Addresses not-working plot clear on augmented plot worlds.

Fixes few mistakes found while debugging and trying out multiple approaches.

When 1.20 adapter is fully functional and ready, remaining adapters should be copied.

TODO:

• Adjacent structures like trees not working (e.g. regenerating Chunk 1;0 - where at edge of Chunk 0;0 a tree is generated with leaves overlapping into 1;0. those leaves are not placed. Same for every other structure or POI)

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