Initial parameters for object

when constructing the new pool object, initial parameters can be defined, and should be for physical objects :
new NapePoolObject(Crate,{ width:20, height:20} , 1); because the body of an object is no longer variable over time, it is best to set body related properties here and not when fetching a new object throught get() because the result will be unpredictable :
- either there is objects left in the pool and you will get() an object from the pool so your new width/height will not be applied because your body already exists...
- or there is no object left in the pool, and because of that you will create a new body with your new width and height. the dimensions of your bodies in your pool will no longer be consistent.