Use git tags and releases

[koppor]

Thank you for the work on this. Would it be possible to tag releases? (I tink, Calendar Versioning would be OK).

When having a git tag, it is also possible to create a release on GitHub based on the tag. Examples: https://github.com/JabRef/jabref/tags - and then click on a tag.

I ask this, because gg.cmd would then be enabled to run the jar directly using gg.cmd gh/fredoverflow/karel (if https://github.com/eirikb/gg/issues/213 is fixed).