F5-F2 - dialog shows summary files size for the list

[Schebi]

When copy files over the list F5-F2 it would be helpful to see the summary files size.

[ghisler(Author)]

Unfortunately this isn't always known, e.g. when downloading a directory from FTP. It can also cause problems when copying locally - for example, when you add a directory, TC would have to check all subdirs for the total size while the queue continues to copy in the background (-> problem with hdd header movement = big slowdown).