patch applied (cabal-branches/cabal-1.2): Bump version to 1.2.3.0 and update the changelog

[Ian Lynagh]

Thu Nov 29 06:39:45 PST 2007  Duncan Coutts <duncan at haskell.org>
  * Bump version to 1.2.3.0 and update the changelog
  There was one minor api addition which requires the minor version bump

    M ./Cabal.cabal -2 +2
    M ./Makefile -2 +2
    M ./changelog -1 +5
    M ./releaseNotes -1 +1