Squash checkmark log in discussion

Summary
Utilizing a few checkboxes on an issue will quickly fill the discussion log making discussions hard to follow and use.

Suggested fix
I suggest squashing them in the same manner as commits are done today. Where checkboxes marked/unmarked are clumped per user and pushed down when a new checkbox is marked/unmarked.

@pedroms Any input appreciated since this is my first issue but I wanted to give weight to this since it's a problem in my projects.