patch applied (cabal-install): Restructure the package installing code

[Duncan Coutts]

Thu May  8 02:26:49 PDT 2008  Duncan Coutts <duncan at haskell.org>
  * Restructure the package installing code
  Previously each layer called the next layer down and therefore the
  top layer had to take all of the params that the bottom layer needed
  even though they were mostly or wholly unmodified on the way down.
  Now each layer takes the next layer as a parameter so we do not need
  to take the params that are not used directly by the current layer.
  The overall stack is then built by applying each layer to the next.

    M ./Hackage/Install.hs -59 +42

View patch online:
http://darcs.haskell.org/cabal-install/_darcs/patches/20080508092649-adfee-0a060fb2225c3e13cfca26ea3fd693bb6a144253.gz