* morlendor must be inside the limits, but not almost the limit of the world
* morlendor are just 220 block but let enought for layers, so reserved 320
* check for nether level or just guess to -11000, error if overlaping
* check if the world is enought to fit the morlendor layers
* close https://notabug.org/TenPlus1/nssb/issues/7
* close https://codeberg.org/minenux/minetest-mod-nssb/issues/7
* the mod only provides spawn automaticlly based on biomes,
this responds so manyu questios about spawn and eggs
* the mod provides specil structures for the bosses of
some mobs, not fully documented
* the mod add new "biome" named morlendor that are only
very deep and its configurable