fixes #217

fixes #189

fixes #215

undefined duration has special handling in the playout so this should be
supported.

fixes #211

fixes #198

fixes #212

refs #127

We often find ourselves adding flex styles to buttons. Instead, this
should be the default.

Although the docs [1] specify a class on Popover components, this
doesn’t seem to be passed down. We help ourselves with a selector for
the data-headlessui-state attribute .

[1] https://headlessui.com/vue/popover

* deactivate buttons and show progress indicator while saving
* place primary button first
* add spacing between buttons
* add support for custom labels for cancel and save

The FormGroup’s save-indicator would jump around when used in
combination with the FormTable. We now have a more tight coupling for
these components so that the FormTable can influence the FormGroup’s
rendering.

fixes #199

Feedback hasn’t been to good, so we remove these again.

refs #206

fixes #203

fixes #209