* Shallow clones

- There is a partial support for 'shallow' repositories that

keeps only recent history now. A 'shallow clone' is created

by specifying how deep that truncated history should be.

Currently a shallow repository has number of limitations:

- Cloning and fetching _from_ a shallow clone are not

supported (nor tested -- so they might work by accident but

they are not expected to).

- Pushing from nor into a shallow clone are not expected to

work.

- Merging inside a shallow repository would work as long as a

merge base is found in the recent history, but otherwise it

will be like merging unrelated histories and may result in

huge conflicts.

but this would be more than adequate for people who want to

look at near the tip of a big project with a deep history and

send patches in e-mail format.