Sky Islands #74
Description
Inspired by the Aether there should be some islands in the sky a few thousand blocks above the player.
There will be some unique structures and bosses.
Reaching the sky biomes should be easy while flying (requires #71)
Additionally there should be some mountains that connect to the sky.
A player will eventually try to climb "that giant mountain in the distance" leading to the discovery of a new world.
The sky islands should not be visible from the ground, until the player gets close enough.
At the current state this requires some changes to the engine to allow generating terrain up there.