Links: Default is follow can we have the option of "nofollow"

At the moment when inserting links we only have the option of the link opening in the current browser page or opening in a new one. (Target) But it is important in SEO that they are designated to be "follow" or "nofollow" they are by default "follow" links, the only way of changing them to "nofollow" is by going into the source code and inserting rel="nofollow" manually. It would be good to have a check box offering the two options.