Added biome system

[Spartan322]

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I tried fooling around to create a crude but relatively expandable biome modification system for the simulation that shouldn't have any noticeable impact on performance, functioning in the state that it is, but given you seem to be trying to implement swimming, something might need to be modified for that to work with this.

Otherwise it should work fine, the changes I've tried with the desert were vaguely noticeable.

Also wanted to see if it would be fine to pull or if it should be left out.

[Hopson97]

Sorry but I gotta add swimming first, me and a friend are practically rewriting the world update function