exec cs process instead of requiring cs module

https://github.com/jashkenas/coffee-script/issues/1620
the coffee-script module isn't documented, everyone seems to prefer exec

Cakefile

@@ -1,19 +1,15 @@
-cs    = require 'coffee-script'
-fs    = require 'fs'
-{log} = console
+{log}  = console
+{exec} = require 'child_process'
+fs     = require 'fs'
 
 HEADER  = fs.readFileSync 'header', 'utf8'
 INFILE  = 'script.coffee'
 OUTFILE = '4chan_x.user.js'
 
 build = ->
-  fs.readFile INFILE, 'utf8', (err, code) ->
+  exec 'coffee --print script.coffee', (err, stdout, stderr) ->
     throw err if err
-    try
-      code = HEADER + cs.compile code
-    catch e
-      log e
-    fs.writeFile OUTFILE, code, (err) ->
+    fs.writeFile OUTFILE, HEADER + stdout, (err) ->
       throw err if err
 
 task 'build', ->

readme.md

@@ -4,6 +4,6 @@
 
 [install nodejs and npm](https://github.com/joyent/node/wiki/Installation),
 install [coffee-script](https://github.com/jashkenas/coffee-script/) with
-`npm install -g coffee-script`, clone 4chan x, cd into it and run
-`npm link coffee-script`. actually build it with `cake build`. for development
-(continuous builds), run `cake dev &`.  kill the process with `killall node`.
+`npm install -g coffee-script`, clone 4chan x, cd into it and actually build
+with `cake build`. for development (continuous builds), run `cake dev &`.
+kill the process with `killall node`.