Add a button for more levels in Generation

I think in Generation for blocks, there should be a button saying add more, and adding ores, you might want them to spawn more lower than higher and at the moment you can only put 1 , if you add a button to add another we can do Spawn from Y=100 to Y=50 and then Y=-5 to Y=50 and have different Ores in Group and Ore groups per chunk. 

Also allows to add more of that Ore in other biomes, want it to spawn everywhere but in 1 biome spawn more often? Well this will allow that