enumerateDates function
Enumerates all dates from start to end, inclusive.
For example, if start is 2016-01-01 and end is 2016-01-02, then two
elements, 2016-01-01, 2016-01-02, will be in the returned iterator.
Implementation
Iterable<Date> enumerateDates(Date start, Date? end) sync* {
for (var date = start; date <= end; date = date.add(days: 1)) {
yield date;
}
}