Issue description: Interface changes one ore into another

What happens: replacing the ore in the middle slot of the Interface will use that ore but continue to process the first ore inserted

What you expected to happen:

Change the ore being processed for smelting

Steps to reproduce:

1. Place desired ore in middle slot of interface
2. Replace middle slot ore with ore not of value
3. Watch as first ingot continues to increase while second ore decreases using the second ore to produce the ingot
   ...

Version (Make sure you are on the latest version before reporting):

• Minecraft: 1.10.2
• Forge:
• Refined Storage:

Does this issue occur on a server? [yes/no]
Yes

If a (crash)log is relevant for this issue, link it here:

[pastebin/gist/etc link here]
Video of process, tested in Single Player
https://youtu.be/3KcxM5fte0Q

This has been fixed as of b3ca436.