Ore Generation Overhaul (noise-based ore spawning)

Ore generation should be based on 3D noise maps, meaning that specific ores will generate in certain areas. Each ore will have an independent noise map that determines where it will generate. Here is the rarity of each "ore vein" and what level they generate at:

• Coal: Coal veins will generate most often between -64 and 64, but may sometimes generate up to 128.
• Iron: Iron veins will generate most often between -64 and 32, but may uncommonly generate up to 64.
• Gold: Gold veins will generate most often between -64 and 0, but may rarely generate up to 32.
• Lapis: Lapis veins will generate between -64 and 0
• Redstone: Redstone veins will generate most often between -64 and -48, but may sometimes generate up to -32.
• Diamond: Diamond veins contain up to 6 patches of 1-3 diamonds (which may be hard to find), and will generate most often between -64 and -48, but may very rarely generate up to -40.