🆕 🎓 Comparable Topic --- Add a topic on comparable

[jameshughes89]

What

Add a topic, or maybe a lab, on extending comparable.

Why

1. Good topic
2. They get thrown a little into the deep end when hitting SortedBag. Having made a class that is comparable will probably help.
3. Good prep for the comparator they use in assignment 4.

Where

After the inheritance topic, but before the bag implementations

Additional Notes

Maybe there's no need for this. They can totally learn it on their own,.and there's only so many hours in the day. Idk. Putting it here to think about for next year.