*
@method codes([fn])
@returns Array
@short Runs callback [fn] against each character code in the string. Returns an array of character codes.
@example

'jumpy'.codes() -> [106,117,109,112,121]
'jumpy'.codes(function(c) {
// Called 5 times: 106, 117, 109, 112, 121
});

*
function(fn) {
      var codes = [], i, len;
      for(i = 0, len = this.length; i < len; i++) {
        var code = this.charCodeAt(i);
        codes.push(code);
        if(fn) fn.call(this, code, i);
      }
      return codes;
    }