change chapter image location and cleanup dead files

MediaBrowser.Controller/Library/ILibraryManager.cs

@@ -115,6 +115,11 @@ namespace MediaBrowser.Controller.Library
         /// <returns>Task.</returns>
         Task ValidateMediaLibrary(IProgress<double> progress, CancellationToken cancellationToken);
 
+        /// <summary>
+        /// Queues the library scan.
+        /// </summary>
+        void QueueLibraryScan();
+
         /// <summary>
         /// Gets the default view.
         /// </summary>