Change Log

[LeoLee5566]

1. Titles of grouping nodes are stored in Exclusion.csv. Please check and make changes if they are not appropriate.
2. The tooltip (hover box) is no longer shared by all courses. Instead, each course can create its own hover box.
3. jQuery.ajax is used to asynchronously check the validity of a URL. (I believe we can do it in pure d3, but I didn't find a tutorial) Also, jQuery can simplify the previous codes(if needed), but I didn't do it yet.

[LeoLee5566]

Change click functionality: the first click will mark the course; the second click will display the tooltip; the third click will unmark the course and hide the tooltip