"Define" feature to reduce duplications

[null2264]

Potential config format:

{
  "define": {
    "ores": [
      {
        "id": "minecraft:iron_ore",
        "weight": 1.0
      },
      {
        "id": "minecraft:gold_ore",
        "weight": 1.0
      }
    ]
  },
  "cobbleGen": [
    {
      "id": "@ores", // id with the prefix '@' will make the mod try to retrieve defined block list
      "weight": 2.0 // overwrite all weight to 2.0
    }
  ],
  "stoneGen": [
    {
      "id": "@ores"
    }
  ]
}