Ssh2-parse-key

--------------------

- Removed debug print statement mistakenly left in place

- Fixed bug where parsing multiple keys could fail as the parser managed
to almagamate them into an unparsable block
- Tweaks to README and infrastructure

- Failed tag and docs generation fixed. No functional changes

- Swapped the [classforge](https://classforge.io/) base classing to
[attrs](https://www.attrs.org)
- Added a lot of additional type annotations to assist with attrs conversion -
this also assists in the documentation markup, These needed to be carefully
handled to make portable to python under travis. Aditionally the
`OrderedDict[str, str]` annotation completely broke mkdocs/mkdocstrings.

Packaging

- Switched to using poetry for development and release
- Updated the `pre-commit` pipeline, with some minor formatting reworks
- Switch to [MkDocs](https://www.mkdocs.org/) for documentation, along with
[mkdocstrings](https://github.com/pawamoy/mkdocstrings/) for API documentation

[0.3.x] - 2020-09-27

- Fixed up documentation
- Added a few additional tests
- This is now reasonably presentable

[0.2.x] - 2020-09-25

- First release
- Documentation build
- CI and release automation