[merge] fetch progress improvements

[Martin Pool]

* Moves away from passing around pb arguments, which I think is
generally a bad idea towards it having being state of the UI.  We may
still have to do it to handle generators.  I'm still thinking about
it.

* Moves debug-flags into a separate help topic.

* Deletes old code from fetch.py.

* Some steps towards better fetch progress indicators but it's not
totally smooth.

* Some developer documentation of the progress api.

* Removes copy-and-pasted fetch implementations in InterRepostitory.
(Please check this, there might have been some reason that I missed.)

* For some reason this reduced the number of round trips in branch,
which is nice but a bit surprising.  I'm guessing some interaction
with generators.

* Tweak the activity display to include scheme and read/write direction.

-- 
Martin <http://launchpad.net/~mbp/>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 20090312-progress.diff
Type: text/x-diff
Size: 49173 bytes
Desc: not available
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20090312/02d277eb/attachment-0001.bin