registering packages in ghc using a directory of package files

[Simon Marlow]

Duncan Coutts wrote:

> Attached is the current patch I'm testing.

I think I've said in the past that in principle I like the idea.  I'll 
commit your patch.

In terms of making this a feature we advertise in the documentation, I 
think we could tweak the details a bit.  I had in mind allowing 
-package-conf to specify either a directory or a file, with the obvious 
interpretation.

Also, with your patch, each file in package.conf.d contains a list of 
packages.  Having just a single package per file seems cleaner, unless 
you have a good reason to want the possibility for multiples.  I realise 
this means wider-ranging changes.

Cheers,
	Simon