Allow Remarkup lists to have checkboxes
Fixes T3945. This provides a convenience style for checkmark lists. They're read-only. See disucssion in T3945.
We're limited on how much we can style the checkboxes -- it would be nice to make them a little more visible, but this seems mostly OK to me. I added some hinting to the item text to make the completion state more clear.
- Added unit tests.
- Ran unit tests.
- Fixed a couple of existing unit test issues.
Reviewers: chad, btrahan
Reviewed By: btrahan
Maniphest Tasks: T3945
Differential Revision: https://secure.phabricator.com/D8931