Expose properties that allow stretching the RatingItems

Add a property to change the direction of the rating.

Add a property to set the orientation of the rating.

Add a property to set the selection mode of the rating.

When rating is created collapsed, switching to visible does not update correctly the value .

The TabNavigation through the rating items doesn't work as expected.
Also when we have a few controls including RadRating with TabIndex set, navigating the first time with tab key works fine. If the rating is not the first in the tabindex sequence, the second navigation over the controls starts with the rating but it shouldn`t.

The RadRating control doesn't show when the IsEnabled property is set to "False".