Basic DS implementation in Java.

Java provides stack and queue as built-in data structures as part of the collections framework. But it doesn't provide Linked List and Trees. Now whenever needed, you may just browse and copy-paste. But that's not smart, and that's not fun. So I am dedicating repository to implementation of such DS. I will impart as much abstraction as possible so anyone who wants to use it can download and use it with least modification.