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

* facilitate new bootstrap-vue table features to get rid of computed table array
* use template slots of the b-table for better rendering
* button group for edit and delete
* implement delete function

* add filesize npm package
* add prettyNanoseconds mixin function

now displaying files and playlists in a b-table or asking to upload something

also refactored groups to shows, after tank refactoring happened

does not work yet, we always get back a 400 when
logo or image are not null in json format

have to find out how the exact format and encoding has to be to update
a show inlcuding files

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

New following a different approach to static assets.

See https://www.jerriepelser.com/blog/using-auth0-with-vue-oidc-client-js/
for how to use OIDC client with the npm sources and per-compile updating
the static asset.

Also environment variables now work a bit differently.

Updated README.md accordingly