Save media when marking all items as "read"

The unreadItems list contains items that are "in progress", so we need
to save the media.

src/de/danoeh/antennapod/feed/FeedManager.java

@@ -435,6 +435,8 @@ public class FeedManager {
 				adapter.open();
 				for (FeedItem item : unreadItemsCopy) {
 					setFeedItem(item, adapter);
+					if (item.hasMedia())
+						setFeedMedia(context, item.getMedia());
 				}
 				adapter.close();
 			}