the gitocalypse repo splitting for v0.3

[Anil Madhavapeddy <anil@xxxxxxxxxx>]

I'm just taking a look at splitting up the Mirage repository for 0.3 and 
wondered if anyone had a strong opinion on the repository history.  I'm 
currently doing this:

- Start with mirage.git from master

- 'Git mv' everything into a set of sub-directories which can operate 
independently.  Each subdir has its own configure/Makefile/ocamlfind script 
which is copied from a common Makefile structure.

- git subtree export everything into separate repositories to host on 
github.com/master

The last bit is the unfortunate one, since it filters out changesets before the 
directory rearrangement and so in practical terms leaves no useful history.  
Ideally (somehow), we would keep the individual commit histories on the files 
even after they've been exported. 

One alternative is to clone mirage.git once per component, and delete 
everything else that isn't needed.  That's a pretty enormous space requirement 
though.

It's a bit tedious, so I'm inclined to preserve copyrights and the original 
repository, and reset the history (as I believe xen-api.git did when 
open-sourced, right Dave?).  Any objections/ideas/agreement?

-anil