ical: Honor completed status of todo items
ical: Honor completed status of todo items

When importing todo items from an iCal file, mark completed items as
completed.

Signed-off-by: Lukas Fleischer <c9ca73f8336dcfb037ec2c2abf52d80a6847a5cd@calcurse.org>

lfos/calcurse,lfos/calcurse,lfos/calcurse