MCA (Headless) generation no longer causes holes, it was a region-chunk synchronization issue when using lots of threads.
Defaulted MCA on, you can disable MCA in the settings if you choose.
Added a small bitwise calculator (/iris bit <n1[,n1,n1]> [>>,<<,&,^,|,%] <n2> for testing & debugging.
If iris fails to generate a chunk, it will generate a flat layer of red glazed clay to indicate it (this usually doesnt happen unless you are on a studio world)
Iris now clamps heightmaps to the min and max of the dimension to prevent unexplained holes, or weird artifacts