remove base58check

Use bs58check package solely from here on.

src/base58check.js

@@ -1,18 +0,0 @@
-var bs58check = require('bs58check')
-
-function decode () {
-  console.warn('bs58check will be removed in 2.0.0. require("bs58check") instead.')
-
-  return bs58check.decode.apply(undefined, arguments)
-}
-
-function encode () {
-  console.warn('bs58check will be removed in 2.0.0. require("bs58check") instead.')
-
-  return bs58check.encode.apply(undefined, arguments)
-}
-
-module.exports = {
-  decode: decode,
-  encode: encode
-}

src/index.js

@@ -1,6 +1,5 @@
 module.exports = {
   Address: require('./address'),
-  base58check: require('./base58check'),
   Block: require('./block'),
   bufferutils: require('./bufferutils'),
   crypto: require('./crypto'),