Added config options for custom mobs to define worlds they can spawn in. (Closes this issue report, which was originally thought to be a Monstrovm issue but it was simply that Better Netherite custom mobs didn't have a way of knowing of custom worlds - Monstrorvm can spawn mobs in custom worlds.)
A much bigger update will be coming soon, this was just to fix this issue beforehand! If you have any suggestions or ideas for this plugin, please suggest them on the Githubs issue tracker, same goes for bugs!