v0.7.5

Changed

• main() runs through duho.run(..., exit=False): it always returns the status
  instead of raising SystemExit for a message, --help or a usage error (the
  console script, python -m dotagents and install.py exit with it as before, with
  the same statuses and the same text on standard error). Ctrl-C now ends with
  status 130 and no traceback, and a closed pipe on standard output ends with
  status 1, quietly.
• The duho floor moves to >=0.7.5,<0.8 (from >=0.6.0,<0.7); the vendored
  .pyz pin (build-pyz --duho-version) moves with it. No flag, exit status or
  output changes.
• Command modules are loaded with duho's own discover_commands(on_error=...)
  instead of a copy of its loop built on a private duho name. A module that fails
  to import is still named in a warning and skipped, and the listing order is
  unchanged. A command module may now import a sibling helper file by its bare
  name.
• kebab_name delegates to duho.text.kebabcase; its results are unchanged.
• Discovered commands are listed in discovery order with discover_commands(sort=False)
  instead of being re-sorted here, and a command that cannot build its parser is
  found out with duho.runtime.build_command_parser instead of a private duho
  helper. Output, exit statuses and which commands are skipped are unchanged.

Full Changelog: v0.7.4...v0.7.5