Add timeout methods

[evgenykuzyakov]

Fixes: #76

This PR also adds ability to update state by passing a function.

Adds four methods:

• setTimeout
• clearTimeout
• setInterval
• clearInterval

Note, that within setInterval, the state is not being updated properly: https://eight-bites.blog/en/2021/05/setinterval-setstate/

if (state === undefined) {
  State.init({
    counter: 0,
  });
  setInterval(() => {
    State.update((state) => ({
      ...state,
      counter: state.counter + 1,
    }));
  }, 100);
}

return <div>Hello World {state.counter}</div>;