When this is set the page will only be rendered to that width. Otherwise 
100% of the available space is used.

Fix bug

* in eager mode a vopStateChangedNotification is still sent
* otherwise the last state is cached in the `VeronaPostService` and
can be retrieved from the host

When form changes the `responseProgress` is determined and sent

Intersection detection is done by `Intersectionobserver`

In the past, the page index could be set by button click and after
scrolling, which led to unwanted side effects

To center the content of the player, the dimensions of all pages are
calculated.

* Move two different intersection detections from
`scroll-index.directive` and `section.component` to
`intersection-detection.directive`

The version is taken from the package.json file and replaced in the 
html.

* Fix bug for small pages
* Add functionality for tabbed pages
* Use layoutContainer as container for intersection detection
* Rename properties and methods

Teststudio does not show patch versions.

Move `MatDialogModule` from editor to common
Add `AlertDialog` to player

Check whether `unitDefinition` or `unitStateDataType` are undefined is
done within the verify methods

* Define data version types data versions for `unitDefinition` and
`unitState` in meta tag of index.html
* Separate `MetaDataService` from `VeronaPostService`
* Extend `MetaDataService` to verify data versions of `unitDefinition` and
`unitState`

When elements are dynamically positioned there is no space below the elements

* Use `IntersectionObserver` to detect page position while scrolling

* Pages can be scrolled or tabbed
* Labels of pages can be shown and hidden
* Always visible pages can be left, right, top or bottom
* Layout of pages is now handled in `LayoutComponent` and removed from
`PlayerStateComponent`
* Due to the `ScrollIndexDirective`, pages with scrollbars have similar
interfaces as pages with tabs