Fix missing papyrus in savanna, add a dry dirt version

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.

mods/default/mapgen.lua

@@ -2143,8 +2143,10 @@ function default.register_decorations()
 
 	-- Papyrus
 
+	-- Dirt version for rainforest swamp
+
 	minetest.register_decoration({
-		name = "default:papyrus",
+		name = "default:papyrus_on_dirt",
 		deco_type = "schematic",
 		place_on = {"default:dirt"},
 		sidelen = 16,
@@ -2156,10 +2158,32 @@ function default.register_decorations()
 			octaves = 3,
 			persist = 0.7
 		},
-		biomes = {"savanna_shore", "rainforest_swamp"},
+		biomes = {"rainforest_swamp"},
+		y_max = 0,
+		y_min = 0,
+		schematic = minetest.get_modpath("default") .. "/schematics/papyrus_on_dirt.mts",
+	})
+
+	-- Dry dirt version for savanna shore
+
+	minetest.register_decoration({
+		name = "default:papyrus_on_dry_dirt",
+		deco_type = "schematic",
+		place_on = {"default:dry_dirt"},
+		sidelen = 16,
+		noise_params = {
+			offset = -0.3,
+			scale = 0.7,
+			spread = {x = 200, y = 200, z = 200},
+			seed = 354,
+			octaves = 3,
+			persist = 0.7
+		},
+		biomes = {"savanna_shore"},
 		y_max = 0,
 		y_min = 0,
-		schematic = minetest.get_modpath("default") .. "/schematics/papyrus.mts",
+		schematic = minetest.get_modpath("default") ..
+			"/schematics/papyrus_on_dry_dirt.mts",
 	})
 
 	-- Bush

schematic_tables.txt

@@ -2100,7 +2100,7 @@ mts_save("large_cactus", {
 
 -- Papyrus
 
-mts_save("papyrus", {
+mts_save("papyrus_on_dirt", {
 	size = {x = 1, y = 7, z = 1},
 	data = {
 		{name = "default:dirt", prob = 255, force_place = true},
@@ -2117,6 +2117,23 @@ mts_save("papyrus", {
 	},
 })
 
+mts_save("papyrus_on_dry_dirt", {
+	size = {x = 1, y = 7, z = 1},
+	data = {
+		{name = "default:dry_dirt", prob = 255, force_place = true},
+		{name = "default:dry_dirt", prob = 255, force_place = true},
+		{name = "default:papyrus", prob = 255},
+		{name = "default:papyrus", prob = 255},
+		{name = "default:papyrus", prob = 255},
+		{name = "default:papyrus", prob = 255},
+		{name = "default:papyrus", prob = 255},
+	},
+	yslice_prob = {
+		{ypos = 2, prob = 127},
+		{ypos = 3, prob = 127},
+	},
+})
+
 
 -- Bush