GitLab

Add "--progress" option and a progress bar display for FEL
transfers. This picks up on a suggestion from Alexander Kaplan
and the discussion at
https://groups.google.com/forum/#!topic/linux-sunxi/lz0oQBwjex0

Signed-off-by: Bernhard Nortmann <bernhard.nortmann@web.de>
Reviewed-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>