* change mu_util_play a bit to better deal with non-ascii filenames

- don't try to encode anything, but pass the filename into the argv for the
    program to open (before we, used g_spawn_command_line_async, and there we
    need to escape things for the command line. Now we use g_spawn_command, so
    we can pass argv as such.
  - add a GError** arg to mu_util_play, and update all callers
  - cleanup the mu-cmd-extract code a bit

widgets/mu-msg-view.c

@@ -134,11 +134,10 @@ on_attach_activated (GtkWidget *w, guint partnum, MuMsg *msg)
 		if (!mu_msg_part_save (msg, filepath, partnum, FALSE, TRUE, &err)) {
 			g_warning ("failed to save %s: %s", filepath,
 				   err&&err->message?err->message:"error");
-			if (err)
-				g_error_free(err);
+			g_clear_error (&err);
 		}
 
-		mu_util_play (filepath, TRUE, FALSE);
+		mu_util_play (filepath, TRUE, FALSE, NULL);
 		g_free (filepath);
 	}
 }