Implement auto-detection of trimmed changelogs

apt changelog is somewhat annoying as AlwaysOnline isn't really always, it just means don't look at the local one, even if it exists. So, NeverLocal might have been a better name… oh well.

As I don't want to break existing configuration this gets a bit strange if you think too deeply about it with --no-online (or --local) which can still go online, but at the end of the day I hope it will do what the user expects more than what is explicitly written down here as --prefer-the-local-file-if-you-can would be way too annoying to type.

The command aliasing is in here as while adding --no-download support I stumbled over way to many options working with auto*, but not auto-*… could have been another branch or left untouched easily.

I think I have the right string for Ubuntu, but I haven't tried. On Ubuntu AlwaysOnline is enabled through, so this only really matters for Ubuntu derivatives which in the best case now have a working setup out of the box.