new Darcs-Repository field?

[Simon Marlow]

Ross Paterson wrote:
> Björn Bringert suggested that the Hackage page for a package should
> include a link to the Darcs repo (if any, but who uses anything else?)
> and maybe some darcs integration such as changelogs and the like.
> To make this work, we'd need a URL-valued Darcs-Repository field in the
> package description.

Trac uses a syntax like 'VC:FILE' for the repo, eg. 'darcs:/home/darcs/ghc'. 
Perhaps we could do the same, something like

source-repository: darcs:http://darcs.haskell.org/happy

or is that too many colons? :)  The syntax of the thing after the 'darcs:' is 
entirely VC-dependent, of course.

Cheers,
	Simon