Floatland biomes: Add forest, tune beach height

mods/flowers/mapgen.lua

@@ -114,7 +114,8 @@ local function register_mushroom(name)
 			octaves = 3,
 			persist = 0.66
 		},
-		biomes = {"deciduous_forest", "coniferous_forest"},
+		biomes = {"deciduous_forest", "coniferous_forest",
+			"floatland_coniferous_forest"},
 		y_max = 31000,
 		y_min = 1,
 		decoration = "flowers:"..name,