update answers_selected

[andreaskutka]

Problem

answers_selected counts only multi select options that are not linked. Linked multi-select questions and list questions are not considered, since they do not have a fixed denominator, defined as n_answers. However, they also carry information. Since analysis is done by variable_name, the number of answers selected could be analysed in absolute terms.

Solution

• remove denomiantor
• add TeXtListQuestions
• add linked questions