Unicorn RL Craft

# Unicorns RLCraft 4

A performance and cleanup update. Singleplayer in particular should feel a lot smoother.

## Performance
- **Much less lag in singleplayer.** If chunks were loading slowly or animals moved like you had bad ping, this is for you. In our testing the world's background work dropped by roughly 40%, even with more mobs nearby, and the multi-second freezes while exploring became far less frequent.
- **Radium is back on.** This performance mod is enabled again, with a compatibility fix for Xenotech included.
- **Removed Spawn Animations.** It was the biggest single cause of lag (around 14% of the world's processing time every tick). The only thing you lose is the "mobs dig up out of the ground" effect.

## Removed
- **BlazeandCave's Advancements Pack** is no longer bundled with the modpack.

## Added
- **MCA Wandering Trader Compat:** the Wandering Trader is replaced by an MCA adventurer villager who uses the regular trades plus extras.

## Loot bags
- **Legendary bags have a lot more to find:**
  - **SWEM** amethyst helmet, chestplate, leggings, riding boots, sword, axe, pickaxe, shovel, scythe and bow
  - **Aquaculture** neptunium armor and tools (including the bow), iron/gold/diamond/neptunium fishing rods, and every fillet knife
  - **Ice and Fire** fire, ice and lightning dragonsteel armor and tools. These are deliberately very rare.

## Fixes
- **Items that refused to stack now stack again.** The fix for items picking up empty data (torches and similar not stacking with fresh copies) was broken and never actually ran. It works now.
- **Quest rewards cleaned up:**
  - The *Pie Time* reward table no longer contains two pies from a mod that isn't in the pack.
  - *Sapling Dance* no longer offers the removed Jacaranda sapling, and the Strawberry sapling now gives the correct item.
  - *Arrow Lottery* no longer hands out a "Frost" tipped arrow from a mod that isn't installed (it used to come out as an Uncraftable Tipped Arrow).

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*Updating an existing singleplayer world:* when you load it, Minecraft may mention that a data pack is missing (BlazeandCave or Spawn Animations). That's expected and harmless.