SuperChunk - Extreme chunk generation

SuperChunk 0.5.0!

• CPU per chunk cut by about 13.6% (29.3 → 25.3 ms on my PC), and 14–24% more chunks per second with identical world output.
• Cells proven solid or air skip the per-block evaluations; about 88% of overworld cells are decided this way
• Neighbouring chunks share edge columns and surface levels plus smaller allocation cuts.
• Cold GPU boot on NVIDIA is faster (436 → 313 s on my pc) with the same output and speed.
• Biomes and geodes match vanilla again (geodes were mostly wrong in 0.4.1)
• GPU programs too large to compile safely now run on the CPU instead, so stuff like Tectonic can no longer OOM-kill the server
• Fixed /save-all flush hanging until the watchdog killed the server
• Fixed stopping the server during chunk generation skipping the world save
• A mod block entity that fails to save no longer breaks the chunk.
• Fixed smaller compatibility issues