ocamldoc generation and packed files

[Anil Madhavapeddy <anil@xxxxxxxxxx>]

I'd really like to generate ocamldoc (HTML/PDF) of all the various libraries so 
that it's easier to learn Mirage (and support editor auto-completion, etc).

The big problem is that ocamldoc doesn't support packed modules, and we use 
packing quite extensively (in Net, Http, Block, etc).

So I've hacked up an ocamlbuild target that concats together the *source* ML 
files from an .mlpack and uses that to generate the ocamldoc for the standard 
library, with one set of HTML files generated per backend (Xen, Net-Direct, 
Net-Socket, and so on).

The issue is that these rules are a little grim: everywhere where we have a 
.mlpack file at the moment, we need to override that rule to generate a 
concatenated ML file that is used for ocamldoc (but not for actual compilation, 
since line numbers get lost since those aren't preserved when converting from 
ML files into a single big one).

Does anyone have a better solution for ocamldoc and packed files? All of the 
grimness here is hidden away in the ocamlbuild rules, so I'm inclined to just 
commit this patch, and perhaps see about adding -pack support into ocamldoc at 
a later stage (there's an open bug in Mantis somewhere). 

Dave, do you use pack in XAPI, and/or ocamldoc?  I wonder if everyone else 
(like Core) also have their own swanky 'cat ML files into one' script too...

-anil