Make it possible for a user to edit or remove his/her own comments

Each user should be able to edit or remove his own comments. Sometimes people put the comment in the wrong place, or want to fix a point that they have made (they hit the "Post" button too soon).

However, only administrators can remove a comment, and no one is allowed to edit a comment.

Please allow a user to edit or remove his/her own comments, but no one else's.