Move applications inside Lets and Cases

[lukaszcz]

The translation from Core to Core.Stripped requires that only variables or function symbols be present at the head of an application.

We need to transform

(let x := M in N) Q

to

let x := M in N Q

and e.g.

(case M of { c1 x := N1; c2 x y := N2 }) Q

to

case M of { c1 x := N1 Q; c2 x y := N2 Q }