Auto-repair upgrade

[ramonGonzEdu]

An upgrade that works similarly to the advanced furnace upgrade but for anvils:

whenever a tool is low on durability, a whitelisted item will be applied on it in an anvil

Before:

• low durability pick
• 1 iron ingot
• 1 xp level

After:

• high durability pick
• 0 iron ingot
• 0 xp level

It should try to repair tools when it will do the most work (ie when it leaves 1 damage) rather than immediately repairing a tool with 1 damage