[PATCH 0 of 4] Progress bar draft

[Stefano Tortarolo]

I've updated the old Thomas's progress bar patches against crew tip.
I've also added a progress bar that doesn't show percentages, useful when the
maxval is unknown, and an example of usage for cloning operations.

It's a simple draft of what could be achieved implementing a progress bar.
The second point of Matthew's thread
(http://www.selenic.com/pipermail/mercurial-devel/2007-July/002453.html)
remains undone.

The 4th patch could be used with this one:
http://www.selenic.com/mercurial/bts/file618/issue1081_clone_verbosity.patch

Note: The enhanced progress bar has been omitted.