A simple set of biomes for now: Ocean, coniferous forest, grassland,
sandstone desert.
Update biome lists for blob ores and decorations.
Make sandstone desert filler 1 node deeper to match other deserts.
Biomes:
Add 'sandstone desert', 'cold desert', 'snowy grassland'.
Rename 'glacier' biome to 'icesheet' biome.
Rename non-swamp 'swamp' biomes to 'shore' biomes.
Remove 'sandstone grassland' biome.
Rename 'stone grassland' biome to 'grassland' biome.
Edit biome points for improved similarity to Whittaker classification.
Change 'tundra' to bare stone with snowblocks.
Make dirt 'swamp' / 'shore' less deep.
Ores:
Make dirt blob ore biome-specific, limit to dirt biomes.
Decorations:
Make mushroom noise spread match that of appletrees as originally intended,
to have mushrooms spawn in darker thicker forest areas.
Add coral reefs in warm oceans.
Add bushes and acacia bushes.
Jungletrees in deeper water for larger swamps.
Register flower mod decorations in singlenode mapgen for use by
minetest.generate_registered_decorations, as in default/mapgen.lua.
Dirt waters are more suitable for waterlilies
Add dedicated dunes biome in coniferous forest
Papyrus: use dirt base again
Force-place roots on mapgen tree schematics
Tune some humidity points to improve voronoi cells
Add random rotation to jungle trees
More complex distribution of dry grasses
Remove water below glacier rivers
Gravel as glacier seabed
Do not force-place acacia root
Tune acacia tree density
Match mgv5/v7 mushrooms to tree density
Spawn mgv6 mushrooms by trees
