Styling of parens

hi,
Going through the code of raven.sc I've noticed that two different are used when closing s-expressions

```
 (if bla
   (do this)
   (do that))
```
vs.
```
(if bla
  (do this)
  (do that)
)
```

when it comes to let expressions, there is
```
(let ((x a)))
```
vs.
```
(let ([x a]))
```

Are there any particular reasons which led to these different styles?


