Rebased version of TheSin's dpkg 1.16.x pull request

This is a rebased and cleaned up version of Justin's pull request #66. This is not yet quite complete, but it should already be a bit easier to review than the old PR. There are a few things that need to be resolved:

* the matter of xz differing from the version in dists need to be resolve
* the matter of dselect being removed from the dpkg.info here, thus causing another difference to dists, needs to be resolved
* probably more...