date-iterator

This crate provides two concepts on top of (chrono)[https://github.com/chronotope/chrono]:

• CalendarDuration that is able to add months and years (which have varying lengths and thus cannot be represented as seconds)
• date_iterators that can be used to iterate over date ranges:
  • OpenEndedDateIterator which never stops
  • ClosedDateIterator which stops after a given date