ts_dwmy_table Generate a time-series of dates with day, week, month and year (dwmy) from one initial to an end years
start year of the time-series, 4 numbers format (e.g 1987)
end year of the time-series, if not provided, current year is used instead
to start the week on Monday, use 'monday', otherwise the week start on Sunday
a data.table object with the date, the day since the first date, the week since the first week, the year, the month, the day in the month, the ISO week number and the day in the week.