Fixed a bug where DateTimeElements don't show any selection animation due to deriving from StringElement, and StringElements only enabling selection if the Tapped event is subscribed to. DateTime elements overload the OnSelected method and so never have a Tapped subscription. Fixed by forcing to always use a selection style.
Merge pull request #173 from Its-Tyson/datetime-element-selection-issue

Fixed a bug where DateTimeElements don't show any selection animation.