MMR - Moog's Mineshafts Reimagined

First port of MMR to Minecraft 1.20–1.20.6.

Added

• Custom #mmr: biome tags so structure biome lists resolve identically across Fabric 1.20.x (where Convention Tags v2 names differ from 1.20.5+) and Forge 1.20.x (which uses the forge: namespace).
• Explicit 1.20.5 and 1.20.6 version mappings so MSL picks the right template per MC, with entity item format adjusted for the 1.20.6 component overhaul.

Changed

• Ported to 1.20–1.20.6. Substituted 1.21-only blocks and entities (tuff variants → stone variants, copper bulbs → shroomlights, crafter → dropper, bogged → stray, decorated pot palette adjusted). Reshaped sign and item NBTs for the 1.20 codec. Renamed structure/ and loot_table/ paths to the plural form 1.20 expects.
• Vault rooms now use chest loot (no 1.20.x equivalent for vaults / trial spawners).
• Replaced the 1.21 guster banner pattern with a 1.20-safe alternative.
• Tuned overworld mineshaft spacing for mansion-tier rarity (ported from 1.21-datapack).

Removed

• Ominous loot tables and trial-spawner pieces (no 1.20.x equivalent).
• 1.21-only processors and 1_21_9/ NBT version-forks (not needed on 1.20.x).