for details see the migration guide for v2.0.0:
https://github.com/bootstrap-vue/bootstrap-vue/releases/tag/v2.0.0

New linter rules:
* curly
* block-spacing
* keyword-spacing

Also apply all autofixes introduced by these rules

Our linting config in package.json was:
```
    "extends": [
      "plugin:vue/essential",
      "eslint:recommended"
    ],
```

Now switching to "plugin:vue/recommended" and apply all auto-fixes

this is syntactically more correct.
also the linter does not complain anymore now :)

When we use the image and logo values in the show object directly,
we get errors, when those values are 0, because they are rendered,
just not visible.

So we use intermediate values now in the this.current object, which
are set everytime the show is switched.

HTML rendering did not work anymore as before - probably due to changes in bootstrap-vue?
So now adapted and in the same time improved rendering.
Now with images for edit buttons.
And if no title is set, this is mentioned now.

Relevant bootstrap-vue docs:
* https://bootstrap-vue.js.org/docs/components/table#custom-data-rendering