Implement Str Class with tests

[demlenar]

Hi There,

I added a string class (Str) that was missing along with tests for it. Does it all look okay? Let me know if there is anything that needs to be updated.

Thanks!

Closes #13

[das-intensity]

Thanks for the PR!

The failures seem to be related to outdated CI setup, unrelated to your changes. Can you try modifying .github/workflows/test.yml to add another env var to Code coverage with coveralls section: GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}?

[das-intensity]

Can you make one more change there, change

run: coveralls

to

run: coveralls --service=github

[das-intensity]

Seems there was an issue with unpinned wrapt on python <= 3.4. I've pinned this in requirements on master branch, please rebase and that should be solved.

[das-intensity]

Looks like github dropped support for pull requests to use secrets entirely. I've updated this on master, please rebase, sorry for all the run-around just for the sake of CI.