patch applied (ghc): Fix Trac #2018: float-out was ignoring the kind of a coercion variable

[Simon Peyton Jones]

Mon Jan  7 06:26:01 PST 2008  simonpj at microsoft.com
  * Fix Trac #2018: float-out was ignoring the kind of a coercion variable
  
  The float-out transformation must handle the case where a coercion
  variable is free, which in turn mentions type variables in its kind.
  Just like a term variable really.
  
  I did a bit of refactoring at the same time.
  
  Test is tc241
  
  MERGE to stable branch
  

    M ./compiler/simplCore/SetLevels.lhs -19 +22