v0.3.1

Changed

• The command line ends through duho.run: Ctrl-C outside netproxy run ends with status
  130 and a closed standard output with status 1, both without a traceback. netproxy run
  still stops on Ctrl-C with status 0. --help, --version and a usage error still raise
  SystemExit.
• The cli extra needs duho>=0.7.8,<0.8 (was >=0.7.0).

Full Changelog: v0.3.0...v0.3.1