UTF8 encoding in Windows

To allow the whole file to be written in Windows you need to append  "\ufeff" to the start of the string.

That makes this line in file.js:
var text = document.getElementById('editor').value;
...become this:
var text = '\ufeff' + document.getElementById('editor').value;

Without this Windows will only write half the text to the file.

Also, great tutorial, and thank you!
