File copy/move: make ETA accurate.
* (progress_update_one): update total progress bytes counter. Update
progress info in the progress window only if file was processed
successfully. Don't check buttons here.
* (move_file_file): update progress info if file move wasn't aborted.
* (copy_file_file): update progress info if stat() or open() failed
(file size is unknown, but file counter shoud be updated). Modify
caclulation and display of byte counters.
* (panel_operate): simplify files processing loop. Remove action that
already done via operate_one_file() call.
Signed-off-by: Andrew Borodin <aborodin@vmail.ru>