add English wordlist and constructor

index.js

@@ -1,10 +1,14 @@
-Crypto = require('crypto-js')
+var Crypto = require('crypto-js')
+var Wordlists = require('require-json-tree')('./wordlists')
 
-module.exports = {
-  mnemonicToSeed: mnemonicToSeed
+module.exports = BIP39
+
+function BIP39(language){
+  language = language || 'en'
+  this.wordlist = Wordlists[language]
 }
 
-function mnemonicToSeed(mnemonic, password){
+BIP39.prototype.mnemonicToSeed = function(mnemonic, password){
   var options = {iterations: 2048, hasher: Crypto.algo.SHA512, keySize: 512/32}
   return Crypto.PBKDF2(mnemonic, salt(password), options).toString(Crypto.enc.Hex)
 }

test/index.js

@@ -1,10 +1,19 @@
 var vectors = require('./vectors.json').english
-var bip39 = require('../index.js')
+var BIP39 = require('../index.js')
+var wordlist = require('../Wordlists/en.json')
 var assert = require('assert')
 
+describe('constructor', function(){
+  it('defaults language to english', function(){
+    var bip39 = new BIP39()
+    assert.deepEqual(bip39.wordlist, wordlist)
+  })
+})
+
 describe('mnemonicToSeed', function(){
   vectors.forEach(function(v, i){
     it('works for tests vector ' + i, function(){
+      var bip39 = new BIP39()
       assert.equal(bip39.mnemonicToSeed(v[1], 'TREZOR'), v[2])
     })
   })