Changed style of highlighted courses (red border instead of gray background)
Added ability to select courses by clicking on them (select multiple with CTRL+click). Clicking anywhere other than on a course will unselect all courses
When you drag courses now, all currently selected courses will be included in the drag so you can move/remove them all with a single drag action
Rewrote most of the state-updating functions to use a library called immutability-helper in order to improve performance
Did a major refactor of mainPage.js so the diffs will be very ugly
resolves #139
Summary
Test
Deployed to d