OK
Slagging fixes.
 * Slag now properly displays that it has content.
 * Worthlessness is red.
 * Smelting furnaces give minerals to slag.
 * Drink glasses and bottles melt properly.
Merge pull request #1841 from N3X15/melting

Slagging fixes.
 * Fixed broken cooled puddle sprite
 * Permit cooling with extinguishers
 * Checks for cooled air.
 * Orange glow.
Merge pull request #1843 from N3X15/melting

Slag - More fixins.
Fix master belt not having a sprite
Wo
Merge pull request #17 from d3athrow/Bleeding-Edge

Bleeding edge