Fix sequence section in chapter 12

[dotnetCarpenter]

This PR fixes most of the issues in #581.

From chapter 12, Type Feng Shui section, I have only changed line 4 from
sequence(Either.of, [Either.of('wing')]); // Right(['wing'])
to
sequence(List.of, Either.of(['wing'])), // List(Right('wing')),
which unlike the original will not throw a TypeError. But also is an example of inverting a Right (List (String)) to a List (Right (String)).
The original, Right (List (String)) to Right (List (String)) made little sense.

Line 5, however is not changed and does not highlight anything particular useful, since
sequence(Task.of, left('wing')) = Task.of(left('wing')).

sequence(List.of, Maybe.of(['the facts'])); // [Just('the facts')]
sequence(Task.of, new Map({ a: Task.of(1), b: Task.of(2) })); // Task(Map({ a: 1, b: 2 }))
sequence(IO.of, Either.of(IO.of('buckle my shoe'))); // IO(Right('buckle my shoe'))
sequence(List.of, Either.of(['wing'])), // List(Right('wing'))
sequence(Task.of, left('wing')); // Task(Left('wing'))

Only two changes was required to support/index.js.

1. Right

traverse(of, fn) {
  return fn(this.$value).map(Either.of); // added return
}

2. Map

  // ----- Pointed Map
  static of(x) {
    return new Map(x);
  }

[dotnetCarpenter]

Blocks #607