Per-action settings

`Interactable#<actionable>({ <setting>: { ... } })`

For example:

```javascript
interact(target)
.draggable({
  restrict: {
    restriction: 'parent',
    elementRect: { top: 0, left: 0, bottom: 1, right: 1 },
    endOnly: true
  },
   snap: {
    enabled: true,
    mode: 'grid',
    grid: { x: 10, y: 10, range: 50 }
  }
}).resizable({
  restrict: {
    restriction: 'parent',
    elementRect: { top: 1, left: 1, bottom: 1, right: 1 }
  },
  snap: { enabled: false }
})
```

Backwards compatibility with the old `Interactable#<setting>({ ... })` is roughly maintained.

`interact#<setting>(...)` is deprecated and may or may not work as you expect. It will soon be removed in a future version.

Closes #87