prepared answerPreviewBox for future changes Task #13968
Task #13968: only one preview button is now shown in newQuestionPanel
Fixed some sass.
Changed options for Task #13968
Added close button to QuestionPreviewBox. Task #13968
Overhaul of some questiontypes in order to show the answers in preview
panel. Task #13968
Added images to preview panel, improved usability. Task #13968