Removed currying from State.setState.

Turns out we don't even need the currying for the `map` parameter, we can just pass the `state.checked` and `state.indeterminate` arrays as argument. :stuck_out_tongue: I just removed the curry helper altogether.

Made `rotateState(s)` accept the DOM element as parameter. This puts it in line with the `setState` signature and makes it easier to work with.