- Use done event of keyboard animation to set the scroll position
of the element
- In small browser views elements are scrolled to the top of the view
instead of the middle of the view

- problem with nullish values

- no event for elements
- only one event für presented pages

- Fix related tests

- FloatingMarkingBarComponent no longer has the elementModel property

- Error was raised when loading a second unit. It was caused by the
binding of the UnitStateService to the UnitMenuComponent

- rename variables, methods and properties
- reduce attributes for methods
- split code in sun methods

- remove prefix 'on'
- split methods

- Remove prefix 'on'

- Remove prefix 'on'

- Rename methods with prefix 'on'

SectionVisibilityHandlingDirective now controls the visibility of
sections that depend on an audio or video