Versioning

[JakobMiksch]

There is an attempt to add Themepark to the (inofficial) osm2pgsql Docker image, see iboates/osm-utilities-docker#12
There the used version of Themepark can only be specified by a commit hash. Example: https://github.com/JakobMiksch/osm-feature-info/blob/d2c00d2/docker/osm2pgsql/Dockerfile#L5 Having a proper version of Themepark would be much cleaner for this purpose.

I am aware that Themepark is still in beta, however it might still be useful to have a prelimniary versioning. Maybe start with v0.1.0. Once a stable version is reached version v1.0.0 could be released.

[joto]

I'll do versions once it is out of beta.