Limit comment threading depth

This is outside of the stated scope of this module, but since you're making so many wonderful improvements to the way comments work, I thought I'd make this request.

Basically we all know how nuts comment threading can get, and how we can end up with a huge number of indentations and very small posts, and this is made especially easier since we can now easily and with good usability, reply to threads in ways that make a lot of sense.

So, I would like to make it impossible to add a comment after a depth of 3.

Comment
-comment
--comment
---comment
----comment NO WORK, auto defaults to->
---comment
Comment

This probably requires hooking into the comment module rather than just javascript, but it would be a superb feature. Thank you for this module.