patch applied (cabal): Warn if no Cabal-version field is specified, but new syntax is used.

[Duncan Coutts]

Mon Aug  6 16:51:31 PDT 2007  Thomas Schilling <nominolo at gmail.com>
  * Warn if no Cabal-version field is specified, but new syntax is used.
  This isn't quite exact.  Ideally, we'd like to have something like
  isEmptyRange (specified-range && >= 1.2) but implementing isEmptyRange
  is non-trivial, so we'll go with this imperfect solution until we need
  that feature elsewhere.

    M ./Distribution/PackageDescription.hs -1 +10