Grid fixes and improvements.

[badnames]

Basics

• [x] I added a line to changelog.md
• [x] The PR is rebased with current master.
• [x] Details of what you changed are in commit messages.
• [x] References to issues, e.g. close #X, are in the commit messages and changelog.
• [x] The buildserver is happy.

Checklist

• [ ] I have installed and I am using pre-commit hooks
• [ ] I fully described what my PR does in the documentation
• [ ] I fixed all affected documentation
• [ ] I fixed the introduction tour
• [ ] I wrote migrations in a way that they are compatible with already present data
• [ ] I fixed all affected decisions
• [ ] I added automated tests or a manual test protocol
• [ ] I added code comments, logging, and assertions as appropriate
• [ ] I translated all strings visible to the user
• [ ] I mentioned every code or binary not directly written or done by me in reuse syntax
• [ ] I created left-over issues for things that are still to be done
• [ ] Code is conforming to our Architecture
• [ ] Code is conforming to our Guidelines
• [ ] Code is consistent to our Design Decisions
• [ ] Exceptions to any guidelines are documented

Review

• [ ] I've tested the code
• [x] I've read through the whole code
• [x] I've read through the whole documentation
• [ ] I've checked conformity to guidelines

[badnames]

I have added lines at y=0 and x=0 to indicate where the origin is on the map. @markus2330 can you please take a look at the usecase and tell me if there is still something missing?

[yvonnemarkl]

jenkins build please

[badnames]

jenkins build please