Another installment on debug mode. This addresses list. However this should...

Another installment on debug mode.  This addresses list.  However this should be considered a temporary state.  The API of the debug database and how vector and list use it, is unsatisfactory at the moment.  It is both inefficient and overly verbose.  I wanted to get this functionality checked in though.  In the next day or so I'll refactor what is there in an attempt to streamline things.

llvm-svn: 140660