#651

#520

- A floating keypad is generated inside a div with the class
  'cdk-overlay-pane'. Now the position of this div is updated when
  dragging the keypad.

The native browser-drag-and-drop does not work in tablets. Therefore 
back to Material which works.
Features are moved over with the exception of replacing items.

- Copy-Lists now always allow putting items back.

- Renew example files
- Update versions and notes

- Set the duration of highlighting anchors to 15 seconds
- Disable simultaneous highlighting of anchors

- Areas are marked with the surrounding 'aspect-anchor' tag

Overwriting styles of HTML elements can lead to unwanted side effects

The whole DOM structure is kind of botched. This is a quick fix and 
should be reviewed.

This was necessary after the surrounding element container with its
styles and classes was deleted

The previous solution, which uses a top position of 50%, did not work on
iPad

See 5ff73e14

This creates a blockquote-element, which is styled globally with 
specific quotes and alignment.

This is the same hack used in the editor for overlay elements. Here 
applied to the actual dnd elements seen in the player.

Explanation: The cursor can not be applied to the dragged elements as it 
is not positioned (at least that is my understanding). The workaround is 
to style the body (cursor) while anything is being dragged.

This avoids duplicate scrollbars in TestStudio

And avoid global styling.

This is rather hard to implement via HTML inline style attributes. So we 
do it the classic way.
Could be reviewed, when that feature is implemented in TipTap:
https://github.com/ueberdosis/tiptap/issues/1514.

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

* 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