Checkboxes only work on + and - bullets

[ayyess]

- [X] foo
	* [X] foo
		a. [ ] foo
		b. [ ] foo
		- [X] foo
	+ [ ] foo
	- [X] foo
		1. [ ] foo
		2. [ ] foo
		3. [ ] foo
		- [X] foo
	- [X] foo
		i. [ ] foo
		ii. [ ] foo
		iii. [ ] foo
		- [X] foo

Toggling the parent checkbox only toggles the currently checked boxes. GFM is also able to handle ~~star~~plus bullets and numbered lists.

• [X] foo
  • [X] foo a. [ ] foo b. [ ] foo
    • [X] foo
  • [ ] foo
  • [X] foo
    1. [ ] foo
    2. [ ] foo
    3. [ ] foo
    • [X] foo
  • [X] foo i. [ ] foo ii. [ ] foo iii. [ ] foo
    • [X] foo