Using a GDateTime improves consistency with the
other components (ideally, we'll move completely
to GDateTime) and simplifies the code.
This commit adds a new property GcalDateSelector::date
and adapts the API to use GDateTime.
There is no subclass of GcalDateSelector, and
actually it isn't needed. So, turn the class
into a final class and get rid of the needless
private field.
Georges Basile Stavracas Neto