updated course dependencies graph

I’ve updated the dependency chart to match the 2019–2020 catalog.

This now includes DATA classes as well as CPE and CSC classes.

As before, the arrows just mean that the catalog refers in some way to the pointed-to course in the prerequisites section; it might be that only one of them is required, or some subset.

Also, colors relate to number of students that have taken a class. Here’s what I wrote before:

The colors relate to the number of students that have enrolled in each class. Specifically, the log of the number of students that have taken the class from fall 2010 through spring 2019. Classes with zero enrollment are given log(0.5). The class with the highest value is red, the one with the lowest value is green. Yes, there should be a legend. Classes that aren’t in the Computer Science catalog are gray.