1.19.0

Improve arg parsing, use userdict instead of extending the base dict class, improve comments, logging. Add tmpdir support

What's Changed

• re-import kwargs after the config by @desultory in #51
• start implementing userdict for the internal config dict by @desultory in #52
• don't use update on unset key by @desultory in #53
• improve comments, fix typos by @desultory in #54
• clean test fs image before re-making, improve config file checks by @desultory in #55
• move out_file to the core section by @desultory in #56

Full Changelog: 1.18.0...1.19.0