Creates and returns a new particle emitter. 
   
   
Parameters


params:Object — - An associative object with a combination of any of the following options.
   
   Available options:
   
   pps - Particles Per Second - How many particles to spew out every second.
    Paramaters: amount
    Example     createEmitter({ pps:50 });
   
   scale - Creates a scale rule that causes the particles to change size over time. 
    Paramaters: [ time, start scale, end scale ]
    Example     createEmitter({ scale:[3000,1,0.2] });
    
   lifespan - Determines how long each particle will live for, in milliseconds.
    Paramaters: time
    Example     createEmitter({ lifespan:8000 });
    
   gravity - Causes the particles to suffer from gravity effects.
    Paramaters: amount
    Example     createEmitter({ gravity:3 }); 
   
   fade - Causes the particle tofade out over time.
   Paramaters: time
    Example     createEmitter({ fade:8000 });
    
   image - Causes the particle to be rendered as a bitmap image.
    Paramaters - a Class object of an embedded bitmap.
    Example
       [Embed(source="man.png")]
       var man:Class;     
       createEmitter({ image:man });
    
   x - Sets the source X coordinate of the particles.
    Example    createEmitter({  x:100 });
      y - Sets the source Y coordinate of the particles.  
    Example    createEmitter({ y:100 });
    
   movement - Determines whether or not the Movement rule should be applied to particles, this rule
              looks at the speed & angle of the particle and causes it to move.
    Example    createEmitter({ movement:true });
    
   minAngle / maxAngle - Determines the minimum and maximum angle that the particle will be pointed in to start with, individual particles will have
    values between these assigned randomly.
    Example    createEmitter({ minAngle:0 });
    Example    createEmitter({ maxAngle:360 });
    
   minSpeed / maxSpeed - Determines the minimum and maximum speed that the particle will start with (in pixels per second), individual particles will have
    values between these assigned randomly.
    Example    createEmitter({ minSpeed:10 });
    Example    createEmitter({  maxSpeed:150 });
    
   size - For dot or line particles, this determines the size of the particle.
    Example    createEmitter({  size:5 });
      color - For dot or line particles, this determines the color of the particle.  
    Example    createEmitter({  color:0xff0000 });
   
   dot - Causes the particles to be a dot shape (circle)
    Example    createEmitter({  dot:true });
   
   line - Causes the particles look like a straight line
    Example    createEmitter({  line:true });
   
   start - Specifies whether or not the emitter should be started right away.
    Example    createEmitter( { start:true } );
                  or
               var emitter = createEmitter( { start:false } );
               // sometime later...
               emitter.start();
    
    pointSwarm - Causes the particles to swarm towards a certain point.
     Paramaters: point
     Example: createEmitter( { pointSwarm:[x,y]} );
    
    mouseSwarm - Causes the particles to swarm towards the mouse.
    Paramaters: stage 
      This paramter requires a reference to the stage so it can set up a mouse listener. 
    Example     mouseSwarm:stage,
   
   rotateToAngle - Causes the RotateToAngleRule to be executed, this causes the particles to rotate in the direction they're traveling.
     Example: createEmitter( { rotateToAngleRule:false } );
   
   xOscillate - Causes the XOscillatorRule rule to be executed, this causes the particle to oscillate back and forth in the X direction.
     Paramaters: [ amount, dampen ]
     Example: createEmitter( {xOscillate:[5,100]} );
   
   tween - Causes the TweenRule to be executed for the particles, this can tween arbitrary values of the particles.
     Paramaters - [ paramater, start value, end value, duration]
     Example: createEmitter( {tween:["x",1,100,3000]} );    
   
   



Returns


IParticleEmitter