fixes for issue #163

[lutzhamel]

The fixes now properly show the stack dump. In particular it fixes the stack dump for the following programs. The first one involving member functions,

structure A with
   data a.
   data b.
   function divide with none do
      return this@a/this@b.
   end
end

let o = A(1,A(2,0)).
o@b@divide().

The second one involving lambda functions,

let x = (lambda with i do return i/0) 1.

and the third one involving expression that compute lambda values,

load system io.

function addc with x do return lambda with y do return x + y end
let a = (addc 1) 1.
io @println a.
assert(a is 2).