Added addAndReturn for easier Component Manipulation

[dlux95]

Sometimes it is useful to return the Component instead of the Entity. Especially when using the Pooled Engine.

With the PooledEngine you can't use the Constructor of a Component to init its values. The Current API forces you to Keep a reference for every Component when you want to modify data in it when adding a new Entity.

This PR introduces the addAndReturn(Compoment component) Method so you can write something like that:

entity.addAndReturn(pooledEngine.createComponent(ComponentA.class)).set(data1, data2)

Where set() is a method that sets the data of the component. That is much more convenient than

ComponentA componentA = pooledEngine.createComponent(ComponentA.class);
componentA.set(data1, data2);
entity.add(componentA);

Especially when dealing with a lot of components.

I also added a unitTest case for that Method which passes. It also won't break existing API behaviour.

[dlux95]

Some comments on that?

[dsaltares]

Sorry for the delay!