Add infinite scrolling to course book table

changed milestone to /AlekSIS%"[NLnet #3] Implement new course book"

added part::frontend type::feature labels

mentioned in issue #256 (closed)

created branch 270-add-infinite-scrolling-to-course-book-table to address this issue

created branch 270-add-infinite-scrolling-to-course-book-table-2 to address this issue

mentioned in merge request !355 (merged)

closed