- Remove unused imports

Windows convertibles were not recognized as mobile devices by this check

#599

- Now every element can overwrite 'getAnswerScheme' of 'UIElement'

- Method is already defined in superclass

#583

#596

#596

# Conflicts:
#	docs/release-notes-player.md
#	package.json

- Not defined intersectionDetector leads to error

Before it was just the bottom helper row.

#592

So it moves away from the "normal" settings.

- New property group for flexible layout with more options to change the 
behaviour. It is now possible to build all other operations in this 
preset.