Agility Kata "Filling Out a Questionnaire IV"

Improve the questionnaire application with the following functions:

1. The questionnaire dialog should display a "percentage completed" number; a distinction should be made between completion with optional questions and without optional questions.
2. The score can be saved in a CSV file with the following structure. Each score is appended to the CSV file so that the CSV file can be used at the end to analyze scores across users and questionnaires.

The CSV file is called scores.csv and is located in the application directory. It has this form:

Title;Question;Answer quality
Questionnaire 1;Which of these animals is a mammal;1
Questionnaire 1;What is the sum of 2+3;0

[1] 1 and 0 stand for correct and incorrect answers