Start setting things out to implement erosion

First up, we're going to attempt to implement a snowballs-based 
algorithm.
Reference: https://jobtalle.com/simulating_hydraulic_erosion.html

worldeditadditions/init.lua

@@ -23,7 +23,7 @@ dofile(worldeditadditions.modpath.."/lib/walls.lua")
 dofile(worldeditadditions.modpath.."/lib/replacemix.lua")
 dofile(worldeditadditions.modpath.."/lib/maze2d.lua")
 dofile(worldeditadditions.modpath.."/lib/maze3d.lua")
-dofile(worldeditadditions.modpath.."/lib/conv/convolution.lua")
+dofile(worldeditadditions.modpath.."/lib/conv/conv.lua")
 
 dofile(worldeditadditions.modpath.."/lib/count.lua")
 

worldeditadditions/lib/erode/erode.lua

@@ -0,0 +1,3 @@
+worldeditadditions.erode = {}
+
+dofile(worldeditadditions.modpath.."/lib/erode/snowballs.lua")

worldeditadditions/lib/erode/snowballs.lua

@@ -0,0 +1,9 @@
+--[[
+2D erosion algorithm based on snowballs
+Note that this *mutates* the given heightmap.
+@source https://jobtalle.com/simulating_hydraulic_erosion.html
+
+]]--
+function worldeditadditions.erode.snowballs(heightmap, heightmap_size, erosion_params)
+	
+end