Make `next` command display next scheduled event

[alexanfl]

The next command will only check if the next date in the calendar is scheduled, not find the actual next scheduled event. E.g., if we have the following calendar,

Thu 1 Jun (no event scheduled)
Wed 14 Jun (event scheduled)

/c next will respond with "No upcoming events.", which is a bit confusing. Should return the next scheduled event in this case.