v0.4.1

Changed

• DUHO_TRACEBACK is read with duho's own truthy values: 0, false, no,
  off and an empty value no longer print a traceback on a reported error,
  where any non-empty value did. The status stays 2.
• A command module's run gets the engine (run(netboot, args, conf)) when
  duho's accepts_positional says it takes three positional parameters. That
  differs from before only for a run whose signature cannot be read (a
  builtin or other C callable), which is now dispatched as a plain run(args),
  and for a functools.wraps wrapper, whose own signature is read rather than
  the wrapped function's.

Full Changelog: v0.4.0...v0.4.1