ParticleEmitter now resets the active particles too.

When reusing particle effects with the ParticleEffectPool, the currently active particles of the effect get not reset. This leads to artifacts when the effect is used somewhere else:

![image](https://f.cloud.github.com/assets/1545118/1101314/e09d4414-17be-11e3-87c7-3d4a06ee60ec.png)

The above picture contains a single particleEffect which is drawn at different positions with freeing/obtaining it between the position changes.

Here the test class from the above screenshot:



	public class ParticleTest extends ApplicationAdapter {
		SpriteBatch batch;
		TextureAtlas atlas;
		OrthographicCamera cam = new OrthographicCamera();
		Vector2 position = new Vector2();
		ParticleEffectPool pool;
		PooledEffect pooledEffect;
		float lifeTime;
		int i;
		
		@Override
		public void create () {
			cam.setToOrtho(false);
			batch = new SpriteBatch();
			atlas = new TextureAtlas(Gdx.files.internal("tmp/packed.atlas"));
	
			ParticleEffect effect = new ParticleEffect();
			effect.load(Gdx.files.internal("tmp/rocket.p"), atlas);
	
			pool = new ParticleEffectPool(effect, 1, 10);
			pooledEffect = this.pool.obtain();
		}
	
		
	
	
		@Override
		public void render () {
			Gdx.gl.glClearColor(0, 0, 0, 1);
			Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
	
			float delta = Gdx.graphics.getDeltaTime();
			lifeTime -= delta;
	
			if (lifeTime < 0) {
				pooledEffect.free();
				pooledEffect = pool.obtain();
				position.set(50 + 50 * (i % 5), 0);
				i++;
				lifeTime = 0.9f;
			}
	
			int v = 200;
			position.add(0, v * delta);
			pooledEffect.setPosition(position.x, position.y);
			pooledEffect.update(delta);
	
			batch.setProjectionMatrix(cam.combined);
			batch.begin();
			pooledEffect.draw(batch);
			batch.end();
		}
	}