List review and overhaul

Game Boy related content is growing fast recently and this list needs some skimming.

We have to review the structure and every link of the list, with the purpose to clean it up and make sure every resource satisfies the "awesome standard" (#96):

- We will be doing this revising blocks of 3-4 links, this thread tracks and links the single github issues about this.
- [MORE.md](https://github.com/gbdev/awesome-gbdev/blob/master/MORE.md) will be the place for everything we remove from the main list.
- Every thread will stay up for 10 days then if there's no opposition or ongoing talk the modifications will be merged in the [`review2020`](https://github.com/gbdev/awesome-gbdev/tree/review2020) branch
- Once 50% of the thread are closed, we start merging the [`review2020`](https://github.com/gbdev/awesome-gbdev/tree/review2020) branch into `master` and the progressively integrate everything

Everyone is invited to partecipate in giving feedback on this.

---

Review threads:

- #159
- #160
- #161
- #162
- #163
- #165
- #166
- #167