Support different kinds of fuels for smelting, beyond 'stick' (smelts 1 item). Better fuel items to smelt more than one (last longer) - likely requires an internal 'heat' value (increased when fuel consumed, decreased when item burned), relates to GH-3
Added fuelBurnTime voxel-registry lookup above (voxel-land sets it for the coal item), but still no customizable smelting time, since everything is instant (requires GH-3 Finite (non-instantaneous) smelting times)
Support different kinds of fuels for smelting, beyond 'stick' (smelts 1 item). Better fuel items to smelt more than one (last longer) - likely requires an internal 'heat' value (increased when fuel consumed, decreased when item burned), relates to GH-3