Agility Kata "Filling Out a Questionnaire III"

Add the following functions to the questionnaire application:

1. For questions, the user may have to enter a text in order to receive an answer. For such questions, only the question and a text input field are displayed. For a free-form answer question, only a text input field and no "Don't know" option is displayed. If the user does not know the answer, they can enter any character to mark the question as answered.
2. Questions may be required or optional. The score can only be viewed after all required questions have been answered. Required questions should be marked in the user interface.

The file format now looks like this:

Which of these animals is a mammal?
Ant
Bee
*Cat
*Dog
??what is the sum of 2+3
2
*5
6
What is the result of 2*3
:6

Questions beginning with "??" are optional, all others must be answered.

An option preceded by a ":" is not displayed, but must be entered by the user.