Better Shadow Diamond Mod Support

[Antirhinnum]

• Modded NPCs are now blocked from dropping Shadow Diamonds if they have dropped one in the past.
• Modded NPCs can no longer drop extra Shadow Diamonds by disabling and reenabling the mod the NPC is from.
• The "Set Shadow Diamond Drop Rule" call method now correctly tells users to use modded NPC types if a vanilla NPC type is provided.

[ExterminatorX99]

Approved