Beginning with efa3fbff39, we separated
the failing and the aborting signals, as they can mean different
things in certain contexts. Still, some places are not yet changed to
reflect this modification. This can cause aborting of progress dialogs
to not work, instead making the application hang in an unusable satte.
This goes through some places where it's not hooked up yet, fixing their
behaviour in those kinds of situation.
Let's move off our custom QuaZip. In the olden times we needed the
custom version of QuaZip, as it was basically unmaintained and on
SourceForge (eww). But nowadays it's maintained and on GitHub. See
new GitHub page: https://github.com/stachenov/quazip
