Events spanning month start and/or end

Problem/Motivation

Events spanning month start aren't shown in the month view if they start before the first day in the month view.

Steps to reproduce

Create an event from, e.g., March 15 to April 30. It will be shown in the month view for March, but not for April.

Proposed resolution

The attached patch changes the filter from checking whether the start date is between the first and last day of the month view. Instead, it filters on whether the start data is before the last day of the month view and the last day of the event is after the first day of the month view.

Remaining tasks

Review.

User interface changes

None. Except, showing events that it previously missed.

API changes

None.

Data model changes

None.