Fireworks effect

Created a fireworks effect component.
FLA: fireworks_cs3.fla

Drag the fireworks component from the library to the Stage.
Modify the component parameters from the Component Inspector Panel. play around with different values for different effect.

parameters:
- burstVelMin/Max : min and max speed of the particles when fireworks explode. randomise. higher, faster
- colour: colour of fireworks
- drag: how fast the particles will slow down. lower number, slow down faster
- gravity: how fast the particle will fall downward. higher number, faster the drop
- numFramesToBurst: number of frames before the fireworks explode
- numParticles: number of particles when the the fireworks explode
- particleLifeSpan: number of frames before particles will disappear
- particleSizeGrowth: how fast the size of the particle will grow. higher number, bigger the growth
- trailDecay: how fast the trail will disappear. higher number, faster
- vx / vy: starting speed in x and y direction