Move NIPageView back into its own file to facilitate its removal and allow clients to avoid pulling in dead code.
Facilitate an easy transition from NIPageView to NIPagingScrollViewPage.
Restore NSString+NimbusCore with calls to NIFoundationMethods
Add debug warnings to get people to remove NSString+NimbusCore
Promote visible pages from the subclassing header to the main header to ease migration.
Restore the pagingScrollView method and add runtime deprecation.