Collection literals

This brings collection literals, as illustrated in:

```
let data = [
  [1, 2, 3],
  tuple[1, 2, 3],
  array[1, 2, 3],
  set[1, 2, 3, 3, 1],
  map[
    ["a", 10],
    ["b", 20]
  ],
  vector[1, 2, 3],
  list[1, 2, 3]
]
```

We also introduced a `gololang.Tuple` class which essentially behaves as an immutable array.

We also added a convenience `getClass()` method to arrays when manipulated as objects in Golo.

Closes #13