OOP chapter editing

I've read through the OOPs chapter and done some changes to make it more like the other chapter regarding the headline names, and done some code changes here and there. 
Generally i think the pointer stuff should be removed, i think it's a very advanced way of looking on classes that should be avoided by new comers if it doesn't give any benefits. 

Also i think the name ofBall should be changed. Classes with the prefix `of` are generally core classes in openframeworks.