[Feature] Hide navigation bar/arrows in quizzes

[rfuehrer]

In testing, it is helpful if navigation to the next question is not enabled until the question has been solved or resolved correctly. Currently, quick navigation using arrow keys may (partially) skip the quiz questions, making it not obvious to the user that interaction is required here.

Possible solution:
Before a quiz, use a data tag (e.g. data-disable-navigation=true) to hide and disable navigation until the solution is found. After the solution has been found, the navigation can be displayed normally again and be usable.

Scaling:
This feature could also be used on other slides before headings to allow navigation via custom text links or links in SVGs.

Disadvantage:
Navigation is still possible via the page structure and users might get an inconsistent impression. However, the user is more likely to navigate via keyboard or navigation bar. With issue #120 this could be fixed.

[andre-dietrich]

I think this is also possible with just a macro. I will have a look at it tomorrow ;-) ...

[andre-dietrich]

deactivating keyboard navigation can be done globally in the following way:

<!--
@onload
document.body.removeEventListener('keydown', getEventListeners(document.body).keydown[0].listener)
@end
-->

# Main Title

The code within the onload section shall remove the only registered keydown listener on the document body. And thus, not react anymore to keyboard navigation ...