Markdown filter: Unchecked check-box is not extracted properly.

[Deepak]

This is extension of the bug #687

The tasklist is defined as follows

- [x] Set up Jersey Shore recording
- [x] Buy donuts with sprinkles
- [x] Take nap
- [ ] Wash ferret

While extracting and merging, the unchecked task ("Wash ferret" here) is not rendered properly

The space is missing within the square brackets causing the issue.

[Deepak]

The changes are committed in local dev with id 3c6b66band a pull request is opened #245

[Kuro Kurosaka]

Thank you for finding and fixing this! I did not know this Markdown filter supports task list (by accident). I think the correct way to support the task list is by adding TaskListExtension in MarkdownParser. But somehow the link reference is handling the task lists.

[Kuro Kurosaka]

Commit ed7ace9 by pull request #245 fixes this with a minor issue fixes this.