#553

- and AnswerSchemeValue with VariableValue

- Remove unused imports

#599

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

- Method is already defined in superclass

#583

#596

#596

Before it was just the bottom helper row.

#592

- 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.

This is a free operation type that does not render much.

#590

#588

#588