An imported event no longer has its end rewritten by the default-duration
setting: an .ics file, a duplicate and an insert intent that names its own
end keep their span, while an intent that gives only a start now gets the
default instead of a hardcoded hour.
Also caps the custom-duration editor at 24 hours, which is what the setting
stores, and skips the calendar query when no per-calendar override exists so
a new event's end doesn't shift after the form is on screen.
Jean-Luc Makiola
5037972fb8