Improvements for calendar export

Problem to solve

Calendar (iCal) export of issues does not include all the information needed by project members when imported to Outlook. This should be improved to make up for the lack of calendar view within GitLab.

Further details

1. Overdue issues (due date in the past) are not included. Why?
2. The default filter is next_month_and_previous_two_weeks but there is no way/documentation to change that. I want to see all future issues no matter when they are due. This is important for long-term planning.

(Include use cases, benefits, and/or goals)

Proposal

Calendar export should include all issues with due date that are not closed.

Also it would be nice to have more options when exporting to calendar like “show past due issues” or “show only open issues”.