patch applied (cabal): Make VersionIntervals an abstract type

[Duncan Coutts]

Fri Dec  5 15:20:41 PST 2008  Duncan Coutts <duncan at haskell.org>
  * Make VersionIntervals an abstract type
  Provide asVersionIntervals as the view function for a VersionRange
  This will let us enforce the internal data invariant

    M ./Distribution/Version.hs -19 +59

View patch online:
http://darcs.haskell.org/cabal/_darcs/patches/20081205232041-adfee-17ad2a221d18b4f4b75f114cd0bbce6b352d90e1.gz