[cs13001] I fixed typos in slides and in examples of the classes lecture

[Mikhail Nesterenko]

Also, In battleship.h of Lab 9 (battleship with classes), I updated
the parameters to be const pass-by reference rather than pass-by
value. You may still use the old version of the header file if you
already stared working on the lab.

Thanks,
-- 
Mikhail