[do-not-merge] Multiple questions, date, salary

This pull requests adds the capability to parse ```[date: identifier]``` and ```[salary: identifier]``` as questions. 
This drove out additional work: before adding these questions, our only question type was "multiplechoice". Now we have multiple question types, several places in the code had to be changed to not check whether an element was a multiple choice, but rather checking if it was a question.