Fix Deprecated Methods on Arena.java, fixes MagicBattle #9

What does this PR do: 

It fixes Issue #9, which was deprecated methods in Arena.java

What else is in the PR:

A List.java class that I removed, realizing that I don't really need it.


Does it work?:

I have no idea, I get no issues with saving it in Eclipse, but it might be a good idea to test it first before rolling it out. I do not have the resources to test it at this time. Although I will in the future.