* display: "one" or "all" (generally "all" for open questions, but...)
* time: 0, //<=0 means "untimed"; otherwise, time in seconds
* introduction: "",
* display: "one" or "all" (generally "all" for open questions, but...)
* time: 0, //<=0 means "untimed"; otherwise, time in seconds
* introduction: "",
* coefficient: number, default 1
* questions: array of
* index: for paper test, like 2.1.a (?!); and quiz: 0, 1, 2, 3...
* coefficient: number, default 1
* questions: array of
* index: for paper test, like 2.1.a (?!); and quiz: 0, 1, 2, 3...
* options: array of varchar --> if present, question type == quiz!
* fixed: bool, options in fixed order (default: false)
* answer: array of integers (for quiz) or html text (for paper); striped in exam mode
* options: array of varchar --> if present, question type == quiz!
* fixed: bool, options in fixed order (default: false)
* answer: array of integers (for quiz) or html text (for paper); striped in exam mode