Not an OP furnace anymore, are ye?

It's been tough.

But the smelter is no longer an OP furnace.

Instead, it takes input from a "phantom" slot (not working yet) as to
what to smelt

But it will only smelt recipes provided.

-Changed smelter to smelt its own recipes, heat dependant, and not
furnace ones
-Removed ability of MachiniTech Ores to be smelted in the furnace
-Added ability to smelt MachiniTech Ores in smelter
-Changed recipe for smelter core to iron instead of copper (Texture
revision needed)
-Changed GUI of smelter to add "phantom" slot
-Changed smelter functionality
-Moved slot classes to their own package,
machinitech.common.container.slot