Project: less
Task (moderate): Class OpenQuestion (file 'common/OpenQuestion.js', 'common/OpenQuestion.less') inherits from Question. Its constructor params are: title (string), name (string), preview (boolean), isMultilines (boolean). When isMultilines is false question value does not contain any line break character. Add a button (class 'add-open') in 'common/SurveyDesign.js', and click it to create an OpenQuestion (random title, unique name) whose root is prepended to the form. Add a checkbox (class 'q-multilines') associated with 'OpenQuestion.isMultilines' to the config panel.