By default, argcomplete uses argcomplete.FilesCompleter as default
for every argument. This mixes accessible files into the list of
possible completions. For most of jw-pkg's commands, that's unwanted,
so turn it off by defining a NoopCompleter class which does nothing,
and by set every arguments's default completer to a NoopCompleter
instance. If desired, completing files can be restored for an
argument by
parser.add_argument("some-arg").completer = FilesCompleter()
Signed-off-by: Jan Lindemann <jan@janware.com>