Move basic search-related code into Core.

Also use qBittorrent torrent file download routines instead of
nova2dl.py script.

src/base/utils/fs.h

@@ -65,7 +65,7 @@ namespace Utils
         QString QDesktopServicesCacheLocation();
         QString QDesktopServicesDownloadLocation();
         /* End of Qt4 code */
-        QString searchEngineLocation();
+
         QString cacheLocation();
     }
 }