Add support for GFM-style checkbox task list

This is from a Google Group post.

Github supports an extension to Markdown for creating checkbox task lists. This MD:

- [x] @mentions, #refs, [links](), **formatting**, and <del>tags</del> are supported
- [x] list syntax is required (any unordered or ordered list supported)
- [x] this is a complete item
- [ ] this is an incomplete item

Turns into this:

• @mentions, #refs, links, formatting, and <del>tags</del> are supported
• list syntax is required (any unordered or ordered list supported)
• this is a complete item
• this is an incomplete item

In case this isn’t obvious: An important aspect of the Github feature that won’t (and can’t) be supported is the the updating of the email (etc.) if the checkboxes are clicked. This makes sense for GH issues, not for email.

[chabad360]

Would be sooooo appreciated! 👍

[stephen147]

You can paste this into the raw text:

<input type="checkbox" class="task-list-item-checkbox" disabled checked>Test line 1
<input type="checkbox" class="task-list-item-checkbox" disabled>Test line 2

It displays like so when converted:

Now, to find a way to change: - [] to <input type="checkbox" class="task-list-item-checkbox" disabled checked>

and

- [x] to <input type="checkbox" class="task-list-item-checkbox" disabled>

This does seem to be possible by wrapping html in the css code as per this: https://www.quora.com/How-do-I-write-CSS-within-HTML https://www.w3schools.com/html/html_css.asp

Same link to where the checkbox code is: http://blog.winddweb.com/implement-github-like-checkbox