Adds world implementation

This is the first attempt at implementing the world class.
I have added some basic functions for adding entites and retreving
entites. There is also the addition of the step function which
retreives a list of systems to process by run priority.
Adds Singleton method to CLMWorld

Adding the singleton method to access the world object
Adds System Implementation

Adding the implementation fo the system manager.
This includes adding, removing, retreiving, and getting a sorted set
based on run priority