Add side by side comparison

[esoccoli]

If you are looking at schedules in order to enroll in classes, you will likely want to compare various schedules to see which one looks the best. It would be useful if there was an option to compare multiple schedules from the results list side by side, rather than having to jump back and forth between them.

[MoralCode]

some similar ideas:

• overlay them onto each other (like semitransparently)
• allow users to "eliminate"/hide certain schedules so you dont have to scroll across a bunch of already-ruled-out schedules if you are trying to, say, compare the first generated one to the fifth.
• have some kind of "add to compare" feature like shopping sites have to let you pick a top 5 or so and then decide from there to reduce the number of decisions that have to be made by the user

This last one could probably be done as an external ics/image/svg comparison tool if there's a desire to do this more quickly

[MoralCode]

possibly related to #106