patch applied (cabal-install): Support top level dependency version constraints

[Duncan Coutts]

Mon Jun  2 04:18:16 PDT 2008  Duncan Coutts <duncan at haskell.org>
  * Support top level dependency version constraints
  and error messages for when they're unsatisfiable or conflict

    M ./Hackage/Dependency/TopDown.hs -13 +38
    M ./Hackage/Dependency/Types.hs -1 +5

View patch online:
http://darcs.haskell.org/cabal-install/_darcs/patches/20080602111816-adfee-78606ba8b9c72ac82febde4bd1cdb503813bb5ee.gz