[0.6.4] Full furnaces waste productivity bonus

[Coolthulhu]

Furnaces that hit productivity bar 100% while their output slot is full will reset the productivity bar without spawning the extra item.
Unlike assembly machines, furnaces won't stop working until they have a full stack on the output +1 item that will immediately get added to stack when it stops being full. Productivity bonus doesn't seem to be able to fill that extra slot.

Tested on electric furnaces, but should work on beacon-boosted steel ones too.

[kovarex]

Thank you for the report.
The same problem was with assembling machine actually, fixed both for 0.7