Hide required courses panel when there are no desired courses #13
Description
Motivation
Currently, when the app is launched the user is greeted with a split pane with empty contents on either side of it (even when the GraphWidget is done it will not display anything since layout-rs panics when you pass an empty VisualGraph). So it would make the app feel more balanced if by default the only thing that shows was the "Desired Courses" view.
Task
Add some app logic in src/lib.rs which by default hides the split view. Then this can either automatically split once the user fills in a course that has a dependency or a button can appear allowing the user to bring up the split view.