correct cross & disappear progress detection

correct cross & disappear progress detection

Given that we use the progress information to skip over actions dpkg has
already done like not purging a package which was already removed and
had no config files or not acting on disappeared packages and such it is
important that apt and dpkg agree on which states the package has to
pass through.

To ensure that we keep tabs on this in the future a warning is added at
the end if apt hasn't seen all the action it was supposed to see. I
can't wait for the first bugreporters to wonder about this…