playlist_song: add flag "secure"

Optionally allow all local files.

"Insecure" mode is used for printing playlists.

src/command.c

@@ -747,7 +747,7 @@ handle_load(struct client *client, G_GNUC_UNUSED int argc, char *argv[])
 {
 	enum playlist_result result;
 
-	result = playlist_open_into_queue(argv[1], &g_playlist);
+	result = playlist_open_into_queue(argv[1], &g_playlist, true);
 	if (result != PLAYLIST_RESULT_NO_SUCH_LIST)
 		return result;