Merge pull request #9 from playcanvas/master

update myself
velocityGraph, localVelocityGraph, rotationSpeedGraph
Scale affects emitter;
Fixed oneShot resetting time and being complex parameter;
Changing graph properties doesn't require full rebuild;
spawnBounds now grow from center and not corner;
spawnBounds now rotate with entity;
Premultiplied and multiplicative blends
fixed rebuilding on velocity graph change
some changes by Vaios
Merge pull request #63 from guycalledfrank/particle-system-update

Particle system update