Function register

register(className: string, classObj: object, recycling?: boolean): void
register an object to the pool.
Pooling must be set to true if more than one such objects will be created.
(Note: for an object to be poolable, it must implements a onResetEvent method)
Parameters
- className: string
  as defined in the Name field of the Object Properties (in Tiled)
- classObj: object
  corresponding Class to be instantiated
- Optionalrecycling: boolean = false
  enables object recycling for the specified class
Returns void
Example
```
// implement CherryEntity
class Cherry extends Sprite {
   onResetEvent() {
       // reset object mutable properties
       this.lifeBar = 100;
   }
};
// add our users defined entities in the object pool and enable object recycling
me.pool.register("cherrysprite", Cherry, true);
```
- Defined in packages/melonjs/src/system/legacy_pool.js:40