Move signature to profile.module

Although we use drupal's integrated forum on our site, we don't allow signatures. However the only way we've found to switch them off is to comment out the relevant code in comment.module.

So for 6.x I'd like to propose that signatures be moved to profile.module and made an optional default - with display moved to the theme level where it should rightly be rather than hardcoded into text area inputs.

Moving signatures to profile.module would do the following:

a. fix the duplicate display issue when contrib modules (signature/flatforum) are used to present signatures dynamically after comments, and give more flexibility to admins. In fact it might eliminate the need for signature.module and that part of the flatforum code altogether.
http://drupal.org/node/62746
http://drupal.org/node/101889

b. Remove what for me is a significant usability issue with the pre-fill - I really don't want to see my signature and type around it every time I post a comment (and hence don't have one on drupal.org) and when I forget to comment out the code we get lots of confused posters who added signatures when they signed up.

c. In addition, as an anti-spam measure etc. I think it'd be a lot better for the signature to be stored once in the database rather than integrated into hundreds or thousands of posts - and be updated for all posts when it changes. That way you have a smaller database, although at the cost of a bit more logic when viewing comments (but less when posting them).

Failing that, an admin setting in comment.module to turn signatures off which:

1. disables the auto-fill in for comment forms

2. removes the signature box from the user edit page

would at least give people a choice.