Papyrus was missing from the dry dirt 'savanna_shore' biome due to
only being placed on dirt. A mistake made when changing savanna
dirt to dry dirt.
Rename existing papyrus schematic to 'papyrus_on_dirt' and only
place in the 'rainforest_swamp' biome.
Add a new papyrus schematic 'papyrus_on_dry_dirt', placed in the
'savanna' biome.
Papyrus:
Make base node dirt instead of dirt_with_grass. Formerly the exposed
dirt would change to grass but the new grass spread ABM now prevents that.
Waterlily:
Don't specify a water_source node in the schematic, as it may be used in
river water. It was not force-placed but should really be "air" prob = 0.
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