copyright issues

FTP masters reported this:

diffoscope\comparators\ar.py has (C) 2016 Ximin Luo <infinity0@pwned.gg> but
the venerated infinity0 is missing from our coypright file

There are a few files that have a mismatch between the d/copyright
file and the files in the source.

There are a few files (such as diffoscope\__init__.py,
diffoscope\changes.py, diffoscope\comparators\__init__.py
diffoscope\comparators\android.py, diffoscope\comparators\apk.py
diffoscope\comparators\binwalk.py) where the license end date is
after the debian/copyright date.

It'd be great to update the d/coypright file with the correct years.