HTML special chars shouldn't be double encoded (as htmlspecialchars do by default) (for 4.2)

1. This allow to use `&nbsp;` as legal symbol in `<option></option>` for example
2. Change encoding to `ini_get('charset_default') ?: 'UTF-8'`
3. In Text box change default encoding from `ISO-8859-1` to `UTF-8`