patch applied (ghc): Monadify simplCore/SetLevels: use do, return, standard monad functions and MonadUnique

[Ian Lynagh]

Thu Jan 17 11:59:58 PST 2008  Twan van Laarhoven <twanvl at gmail.com>
  * Monadify simplCore/SetLevels: use do, return, standard monad functions and MonadUnique

    M ./compiler/simplCore/SetLevels.lhs -111 +100