Redraw the view after an orientation change

When subclassing the view an overriding `layoutSubviews` (to use autolayout for example), the view is not redrawn after an orientation change.
The call to `setNeedDisplay` is currently done in `layoutSubview`. This PR propose to add a call to `setNeedDisplay` in `deviceOrientationDidChange`. There will be no performance cost when using the vanilla GDIIndexBar, as the `setNeedDisplay` calls are buffered and the view will be redrawn just once.