Events with out end date/time are 'multiday'

Currently, if an event doesn't have an end date/time, it's considered multiday in the theming. This really causes problems for people that don't enter end dates for calendar items.

For example, let's say we have a meeting that starts on January 1 at 5pm. We don't know (or schedule) an end time the same day (maybe it will end at 6, or maybe 8, or whatever) so there isn't one entered into the calendar. This event is considered 'multiday'.

An event should be checked to make sure it actually spans into a second day before it's considered 'multiday'.