QuickLook Changes for Swift

	Name	Declaration
From	QLPreviewRequestRef	typealias QLPreviewRequestRef = QLPreviewRequest
To	QLPreviewRequest	class QLPreviewRequest { }

	Name	Declaration
From	QLThumbnailRef	typealias QLThumbnailRef = QLThumbnail
To	QLThumbnail	class QLThumbnail { }

	Name	Declaration
From	QLThumbnailRequestRef	typealias QLThumbnailRequestRef = QLThumbnailRequest
To	QLThumbnailRequest	class QLThumbnailRequest { }