Add CodeMeta file

[oschulz]

See https://escape-ossr.gitlab.io/ossr-pages/page/contribute/publish_overview/ and https://codemeta.github.io/

[Cornelius-G]

I used the OSSR Codemeta Generator to generate a codemeta.json:
codemeta.json
@oschulz Feel free to modify or to add to the repo.

[oschulz]

Thanks! I'll take a look regarding fine-tuning.

[Cornelius-G]

Some updates: codemeta.json