patch applied (cabal-install): improved error handling for multiple installs

[Isaac Jones]

Mon Dec 31 13:03:03 PST 2007  ijones at syntaxpolice.org
  * improved error handling for multiple installs
  When installing multiple packages, don't quit just after the first
  error, but rather collect the list of packages that failed to install
  continue installing whatever packages we can, and provide an error
  message at the end.
  

    M ./Hackage/Install.hs -2 +15