* bring in the art assets from ClockGen's "better_caves_modpack" under CC BY 4.0,, code written from scratch.
* update mapgen_helper
* import ClockGen's giant mushroom schematics, make them and giant ferns growable
* add giant jungle mushroom, rough out actual cavern layer code framework
* fungal ceiling decorations
* decorate fungal floor a bit
* update mapgen_helper
* update primordial mushroom schematic placement to ensure it fits
* add giant mycelium fungoidal structure
* add giant mycelium to mapgen
* fix settings for giant mycelium
* make mycelium grow when players aren't present
* allow mycelium growth to pause when it hits unloaded areas
* add a use for giant mycelium
* make giant mushrooms edible, make jungle trees growable
* rough out the jungle biome
* Make a spectrum of jungle growth
* optimize pngs, add is_ground_content to everything
* use custom is_ground_content method
* fix a crash with veinstone, and simplify nvals_cave lookup now that overgen covers the same area
* more fixes for overgen support
* remove unintentional airspace from underside of slade
* fix for overgen crash in level 2
* primordial column material, add sealed shafts to underworld
* add seal block
* Set up puzzle seals to be able to dig a staircase shaft through the slade layer. TODO: the puzzle to guard the trigger.
* puzzle seals now fully functional. Need to add clues for decoding the keys next.
* add a small bit of anti-griefing - the seal breach bell only tolls globally 13 times per activation
* add flowers to the underworld warrior bones
* switch to a different key bell
* fancy up the puzzle seal temples with some custom blocks, add sub-slade grid passages
* add a clue to the seal formspec
* tweak background of inscription 2 so it's less obviously a copy of the background for inscription 1
* switch to compositing to save a few bytes
* fancy up the seal's upper surface with inscriptions to make the formspec feel consistent
* puzzle particle, bones were only spawning on top of structures
* fix ice/oil on level 3, tweak some loot probabilities
* add trail mod support
* remove deprecated files
* boost default plant growth delay, add growing selection boxes
* update map colours
* add named waypoints to the underworld
* try a more efficient way of changing the interiors of columns
* polishing up the Primordial layer
* update guide with some Primordial teasers
* updated magma sea screenshot
* update mapgen_helper and subterrane
* reduce density of megaflora a bit - was too hard to walk through
* spreading_dirt_type depends on light, create my own ABM instead
* add names to the glowing pits and some of the ruins
* separate setting for ruin markers
* record identity of slade-breachers
* make mycelia climbable
* update subterrane
* change surface tunnel detection to allow above-ground stalactites and stalagmites
* add rare thicker Goblin Caps, suitable for use as huts.
* better goblin cap schematics
* update colours
* make it slightly harder to dig down through amethyst sheathing of pits
* fixing up fungus light sensitivity, tree growth code
* fix a few minor bugs
* update deprecated functions
* add various eating sounds
* make mapping kit requirement more flexible
* update spindlestem growth code, remove deprecated functions
* fix leftover undefined variable
* add fireflies to primordial, spread out the post-mapgen node timer for plant matter a bit more.
* fix bones formspec
* add lbm to upgrade old bones
* fix slade undiggability
* make torchspines smokey and manually lightable
* fix drop definitions
* generate dry stalactites in near-surface caverns.
* caverns become far too smokey, alas
* add pitter patter of spore tree spores, alternate paper recipe
* new mapgen_helper metrics
* add smokey back to torchspine now that it can be dialed down a bit
* replace glowstone texture with a new animated one
* switch from ABM to node timer for mapgen mycelium growth
* make mapgen mycelium timer delay configurable
* improve the efficiency of giant mycelium growth using flat node array, fewer dereferences
* remove the smoke from torchspines again - it doesn't dissipate that deep underground
* give slade a more muted, gloomy hue to differentiate it from nether stone
* update screenshots with new slade colors
* update mapgen_helper
