[Haskell] Haskell-mode 2.3

A few minor typos/thinkos plagued Haskell-mode 2.2, so here's 2.3. http://www.iro.umontreal.ca/~monnier/elisp/ No significant change, apart from the inclusion of a haskell-cabal-mode for Cabal description files (doesn't do anything useful, tho, other than highlight comments). Stefan