Decompiler Enhancement: re-sugar tuple let expressions

```
e.g. the following is currently incredibly verbose:

    source <@ let a,b = (1,2) in a,b @> =? 
        "let patternInput = (1, 2) in let b = (let _,item2 = patternInput in item2) in let a = (let item1,_ = patternInput in item1) in (a, b)"

```

Original issue reported on code.google.com by `stephen....@gmail.com` on 27 Mar 2011 at 7:01
