Fix to progression from stone to iron

I suggest that iron should be harder to obtain in the early game.

To make the progression of the game better let´s make it so that only the blast furnace can smelt raw ore to ingots, and the Armorer Villagers can trade for Ingots. 

To make Iron more valuable in the early game, the blast furnace should also require soul soil to melt ores. this makes sense as soul flames are hotter. 

This way the player can get iron ingots and gear by exploring structures, defeating mobs, and trading with villagers before getting to the Nether, and can get unlimited iron after reaching the Nether. The player also has a reason to visit the Nether to get soul soil.

This makes the game only a little harder in the early game and makes the early game more enjoyable and longer, while solving the issue with very minor changes to the code and implementation.