Title says it all.
This is a program called master plan.
It was designed for campaign planning, and though i haven't gotten into more than the calendar, cause that is what I was looking for, Much of the campaign planning looks usable for any system even though it was original designed for D&D 43.
This game allows to you assign what ever many days to each month.. variable # of days to your week, Enter Holidays that fall between months as Months themselves with just 1 day (or as many days as the holiday takes) You can assign the seasons. You can assign special events/holidays within the months. You can assign Multiple moons with what ever phases and time period you like. you can even assign Leap years # of days and How many years the leap rotates.
I really do recommend this !
http://www.habitualindolence.net/masterplan/
