Implement GemKnife

[cpaca]

Util.shulkerForEach(box, action) does these 3 steps at once:

• Gets the shulker-box's inventory
• inventory.forEach(action)
• Saves the shulker-box's inventory.

Why?

Honestly? I wanted to have a shulker-box of momentos. However, I do vaguely remember something about wanting "holoitems with inventories" (gem knife, quartz blossom, corrupted wheat seeds, watering can, hourglass, rift walker) to not have their own inventory, and instead take stuff from the player's inventory.

Therefore, shulkerForEach is meant to make it easier for these items to also search shulkers inside the player's inventory. Notably, gem knife (with this) won't require you to take the emeralds out of shulkerboxes.

Did you say "shulker-box of momentos" earlier?

My test subject of choice was to make a holoitem that's the same as a shulkerbox, but when you die it'll trigger any momento abilities that are also inside of the shulker-box.

To be clear, I'd been theorycrafting this for a while, though today's ARH session is what pissed me off enough to implement this immediately even though it's a new holoitem. (Additionally, I'd forgotten Gem Knife exists, and Momento is already implemented so in theory it shouldn't be too much ontop of that.)

What are these changes in BlockAbility?

Well, to make a shulker box custom item, I couldn't figure out how to get it work as an enchantment. I swapped it to a custom item, but it kept deleting the contents, so I wrote some stuff in BlockAbility so it'd stop doing that.

Balance problems/too weak/strong/don't like it/will not add to main server/etc.

The main purpose of this commit was for Util.shulkerForEach. LibraryShulkerBox doesn't have a recipe, and I sprung this all on you without any warning. I don't mind that much if LibraryShulkerBox gets deleted, although I will be a little sad since it's useful for reducing the number of inventory slots I'm using.

That said, the changes I made to BlockAbility might be helpful for future shulker holoitems, so those might be worth a keep as well.

[cpaca]

I just remembered - when I was testing this with other colors of shulkerbox, it wasn't working. Can either continue working on that, or scrap library of memories, or scrap the entire branch (and decide gem knife won't get to take emerald blocks from your inventory)

[dlee13]

Everything you did to BlockAbility is wrong. You're supposed to do that in an Override on LibraryShulkerBox. Save the box contents, call the super method, then set the box contents.