remove deprecated module(), better README

README.md

@@ -11,8 +11,9 @@ The heightmap module uses the diamond-square algorithm to generate cloud or plas
 Usage
 -----
 
+```lua
 -- import module
-    require "heightmap"
+local heightmap = require "heightmap"
 
 -- create 32x32 heightmap
 map = heightmap.create(32, 32)
@@ -38,6 +39,7 @@ Usage
 
 -- use the custom height function and normalize with a range of 10 to 20
 map = heightmap.create(200, 200, f, 10, 20)
+```
 
 How it Works
 ------------

heightmap/heightmap.lua

@@ -3,8 +3,6 @@
 
 local max, random = math.max, math.random
 
-module(...)
-
 -- Find power of two sufficient for size
 local function pot(size)
     local pot = 2
@@ -88,13 +86,13 @@ end
 -- d is depth (from size to 1 by powers of two)
 -- h is mean height at map[x][y] (from square/diamond of radius d)
 -- returns h' which is used to set map[x][y]
-function defaultf(map, x, y, d, h)
+local function defaultf(map, x, y, d, h)
     return h + (random()-0.5)*d
 end
 
 -- Create a heightmap using the specified height function (or default)
 -- map[x][y] where x from 0 to map.w and y from 0 to map.h
-function create(width, height, f)
+local function create(width, height, f)
     f = f and f or defaultf
     -- make heightmap
     local map = diamondsquare(pot(max(width, height)), f)
@@ -104,3 +102,8 @@ function create(width, height, f)
     map.w, map.h = width, height
     return map
 end
+
+return {
+    defaultf = defaultf,
+    create = create
+}