Cmdkit

- Fix update behavior for Configuration
- Update documentation
- Minor fixes to code correctness

The original implementation inherited by Namespace only coerced member
mappables to a Namespace on access (read) and would clobber any in-place
changes made to the structure. Now we coerce on set (write) and so
modification works perfectly well.

Minor fixes and improvements to the code. This also includes some refactoring that make it easier to patch behavior. Additions to CI/CD improve automation for the project.

This release includes a number of fixes and improvements. The notable feature addition is the ability to now add non-terminating options and flags to an `ApplicationGroup` interface and have them available in your applications. All groups along the hierarchy have their option namespaces merged and attached as `shared` to the Application class. So adding `my_opt` to a parent application group would be accessible from the downline application as `self.shared.my_opt`.