"new_deb822" and "case_insensitive_keys" merge

[John Wright]

Dato,

Hi!  Sorry I haven't been working on this much lately.  I finally got
around to merging your apt_pkg stuff with my case insensitive keys
branch.  It's available here:
  http://free.linux.hp.com/~jswright/deb822/apt_pkg_integration
There's still a test failure I need to fix, and there are probably yet
tests to be added, but it's a start.

I wound up adding the _parsed dict handling to the Deb822Dict class, to
avoid having a bunch of overridden dict methods in the actual Deb822
class.  I'm open to suggestions and/or criticism, as always.

I'd like to get the API pretty well finalized (or at least stable enough
that new releases will be backwards compatible) and upload to Debian in
the next few weeks, so if you want to see any major behavior changes,
now's the time. :)

Thanks!
John Wright