[DaysOfWeek] Improved Detection of best Date Style

-Added Enum to differentiate the DaysOfWeekStyles
-Added displayStyle Function, which return the DisplayStyle to use. Can
be overridden in subclasses.
-Added Algorithm to automatically choose the right DisplayStyle based
on frame size instead of orientation.
-Moved the Label (Re-)Generation to the updateWeekdayLabels function.
-Edited the dayOfWeekLabelFont method so it always return the same font
Size regardless of the device orientation
-removed (now unnecessary) methods to detect the Device Type and
Orientation.