Several RSS fixes:

- Fix possible redownload of torrents marked as read (Closes #927495)
- Properly remove RSS feed settings/history upon feed removal
- Fix possible crash in RSS Downloader dialog in debug mode

src/rss/rssmanager.cpp

@@ -48,6 +48,7 @@ RssManager::~RssManager(){
   m_refreshTimer.stop();
   delete m_rssDownloader;
   RssDownloadRuleList::drop();
+  saveItemsToDisk();
   saveStreamList();
   qDebug("RSSManager deleted");
 }