Make "git clone" less of a deathly quiet experience

Make "git clone" less of a deathly quiet experience

It used to be that "git-unpack-objects" would give nice percentages, but
now that we don't unpack the initial clone pack any more, it doesn't. And
I'd love to do that nice percentage view in the pack objects downloader
too, but the thing doesn't even read the pack header, much less know how
much it's going to get, so I was lazy and didn't.

Instead, it at least prints out how much data it's gotten, and what the
packing speed is. Which makes the user realize that it's actually doing
something useful instead of sitting there silently (and if the recipient
knows how large the final result is, he can at least make a guess about
when it migt be done).

So with this patch, I get something like this on my DSL line:

	[torvalds@g5 ~]$ time git clone master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6 clone-test
	Packing 188543 objects
	  48.398MB  (154 kB/s)

where even the speed approximation seems to be roughtly correct (even
though my algorithm is a truly stupid one, and only really gives "speed in
the last half second or so").

Anyway, _something_ like this is definitely needed. It could certainly be
better (if it showed the same kind of thing that git-unpack-objects did,
that would be much nicer, but would require parsing the object stream as
it comes in). But this is  big step forward, I think.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>