Suggestion:add weight support for custom recipes

[zomb-676]

It appears that a recipe can have different output products,Modular Machinery now can set chance for each of them. But each of them are calculated Independently the possible output will be zero,one,two or even three.

But I want to set weight for them. It means that the output product will be only one which is calculated according to the weight I set.In the above case.There's a 20%(20%+5%+0.1%) percent chance that I will get the Iron.

[voidsong-dragonfly]

I would like this as well, something like

{
    "type": "weighteditem",
    "io-type": "output",
    "items": ["minecraft:fire_charge", "minecraft:blaze_powder", "minecraft:coal_block"],
    "weights": [0.2, 0.5, 0.01],
    "chance": 0.5,
},

where you only get one of those items, an item only 50% of the time, and there's a 20% chance to get the fire charge.