[Development] Calendar classes: API review request

[Edward Welbourne]

Feature freeze is drawing near, as Jani just reminded us,
and Soroush's work on calendar support is in a state that
looks (to me) ready to use.

Please would those with strong views on API design take
a look at [0] and speak up now, so that we don't end up
reworking it all during the API review phase of the release.

* [0] https://codereview.qt-project.org/182341

This would also be a good time to take a look at Hamed's
related work in QML:

* https://codereview.qt-project.org/228407
* https://codereview.qt-project.org/188184

	Eddy.