Comments related to outdated code are improperly displayed

The display of comments on diff currently doesn't take into account the version of the diff. This lead to at least two issues:
1. if the diff is shorter and the comment is attached to a line number that is no longer present in the diff, then the comment cannot be attached to the diff at all and so is not displayed
2. the comments attached to outdated code are not emphasized as outdated so we could display comments that are not at all related to the line they are attached to