Terra++ v2.0

[DaMatrix]

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this pr will completely revamp how terra++ handles datasets and presets.

• configuration for scalar datasets (elevation, etc.) will be stored online, allowing for default datasets to be updated without having to force t++ updates
• migration away from AWS terrain tiles - i'll be hosting everything myself, and improving support for dataset mirroring as well. this will allow us to avoid the huge number of dataset bugs that come with it (e.g. #16, https://github.com/tilezen/joerd/issues/199, to name a few)
• everything will be stored in the world generator options. this means that the terraplusplus/config directory will be no more! you'll be able to share everything required to generate a world simply by duplicating the preset file.

for users who are using custom elevation datasets, these changes will be breaking.

[FireFragment]

How is this PR going and what needs to be done yet? Do you plan to continue developing this PR? (last commit was done a year ago) I'm eager for features planned in #43 😀 of which development is planned after completition of 2.0

Maybe, if I will have time, I could help with something

PS: I appreciate your work a lot, keep it up!