not whether an argument of a constructor is in normal form

case [a] of { [b]->(b,b) }

transformed to

  let b=a in (b,b)

now it transfroms to

  (a,a)

before
  case x of { 1->1; _ -> case C of { A -> 2 }}
transformed to
  case x of { 1->1; _ -> neverMatchingCase }
now it transforms to
  case x of { 1->1;}

completing Sjaak's changes in module trans caused by exchanging the transform and convertcases phases

 - dictionary arguments added properly
 - coercion of function types

function determinePriority added