More powerful destructuring

Spider already supports:

```
var [a, b] = [1, 2];
[a, ,b] = [1, 2, 3];
[a, b] = [b, a];
```

Spider also supports splats `...rest`.

Spider should support the following (It may support some of these already):

```
var {a, b} = {a: 1, b: 2};
var {first: a, last: b} = {first: 1, last: 2};
var [a, b, ...rest] = [1, 2, 3, 4, 5];
var {a, b, ...rest} = {a: 1, b: 2, c: 3, d: 4}; // rest = {c:3, d:4}
```

Also in function parameters:

```
fn obj({x, y, z}, color){...}

// which is called like this:
obj({x: 1, y: 2, z: 3}, 'blue');
```

This would all be extremely useful in a lot of places, and are features that libraries like React will soon depend on. Most of these features are part of ES6. the `...rest` in an object is not, but it is a proposal. JSX will be adding support for it anyway.