Belgian intrastat report

Belgian Intrastat report in 1 module for V8.0
It is relatively safe here, but keep in mind that date.today() will be in UTC timezone... so if used very closed to the beginning or end of the month, for a user in a remote time zone (e.g. Japan), there is a chance the month will appear to be off by one. There is a utility method `fields.date.context_today` that will return the date in the user's time zone, but it returns a string (you'd have to re-parse it using SERVER_DATE_FORMAT).