darcs patch: fix #1839, #1463, by supporting ghc-pkg bulk queries with substring matching

[Duncan Coutts]

On Thu, 2007-11-15 at 02:14 +0000, Claus Reinke wrote:

>      substring matching can optionally ignore cases to avoid the
>      rather unpredictable capitalisation of packages.

If this is up for discussion, it'd be useful if ghc-pkg did not allow
the same version of packages that differ only in the case of their name.
It'd make moving to treating package names case insensitively easier.

Duncan