Trowel & Error

🔧 Bug Fixes
• Fill Down Trowels (both standard and random): now fill 3 blocks wide (center, left, right)
  when clicking the top face, matching the behavior of Torojima's original Fill Down Wand.
  Previously, they only filled a single column forward from the edge.

✨ New Trowels
• Random Universal Fill Trowel
  – Quickly fill large areas with a mix of the base block and related variants
    (e.g., stone bricks → cracked, mossy, chiseled, and plain stone).

• Random Exchange Trowel
  – Exchange blocks from one type to another, with random variants added to the mix.

• Random Fill Down Trowel
  – Same as the standard Fill Down Trowel, but places random relatives of the target block.

• Fire Trowel
  – Inspired by Torojima's Arrow Wand, but with a fiery twist – sets targets ablaze!
    (Use with caution.)

⚙️ Improvements
• All random trowels now read from a configurable JSON file (`variants_config.json`)
  for easy customization of block families and variant lists.
• Fill Down Trowels now fill through water and lava as well as air, making it easy
  to fill lakes and lava lakes.