#530 thread collapse on D2

[shane]

The little "L" graphic that denotes an indentation of a thread. Can we
make that clickable such that it will collapse all children underneath it?

Right now you can click on that comment's subject, and it'll collapse that
one comment.

The reason for this - if a thread in the discussion is going off into lala
land, I want an easy way to get rid of it (w/o a page reload) w/o having to
change the full/abbreviated/hidden levels). Just get it out of my sight so I
can read the other threads below it.