Add inkelyad's smooth transitions, add config option for this.

config.lua

@@ -5,3 +5,6 @@ snow.enable_snowfall = false
 
 --Enables debuging.
 snow.debug = false
+
+--Enables smooth transition of biomes.
+snow.smooth = false

mapgen.lua

@@ -114,6 +114,7 @@ if maxp.y >= -10 then
 		end
 
 		local make_pine = snow.make_pine
+		local smooth = snow.smooth
 
 		--Reseed random.
 		pr = PseudoRandom(seed+68)
@@ -133,8 +134,15 @@ if maxp.y >= -10 then
 			local z = z0+j
 
 				--Check if we are in a "Snow biome"
+                local in_biome = false
                 local test = perlin1:get2d({x=x, y=z})
-			if test > 0.53 then
+                if smooth and (test > 0.73 or (test > 0.43 and pr:next(0,29) > (0.73 - test) * 100 )) then
+                    in_biome = true
+                elseif not smooth and test > 0.53 then
+					in_biome = true
+                end
+                
+                if in_biome then
                 
                  -- Find ground level (0...15)
 				local ground_y = nil