Repository maintenance (..., long inline documentation)

The following actions would increase the focus of the repository in GitLab. All actions are available in the repository settings.

1. Upload the project logo as the repository logo.
2. Add relevant tags to the GitLab repo: OpenStreetMap, 3D viewer
3. Deactivate the GitLab Wiki, if it is not supposed to be used.
   • It would be a good place to define the goal of the project. But it seems the OSM wiki is used for that.
4. Deactivate GitLab’s repository.
5. Deactivate GitLab’s Maven packages.
6. Deactivate GitLab CI as long as there are no building steps or tests.
7. Move long inline documentation into Markdown files