Effects Engine

As with the animation system and the UI, the particle effects engine need to be completely exposed to Lua as it will be directly used there. Effects will be played on spell casts, and some flexibility is required:
### Directional effects

Some effects need to move from the spawning position (the original scene node) until a destination is reached (usually a set target node, or an arbitrary world position). Directional effects can not be timed, and thus have to be terminated manually when the destination is reached. An example effect is a Fireball shot from the hero against the opponent hero.
### Trailing effects

Some effects need to follow a scene node.
### Stationary effects

Some effects need to stay at their spawning position regardless of the attached scene node position.
### Chained effects

Probably the most tricky, some effects will be composed of multiple effects that need to fire off sequentially. An example spell is a Comet, where the fiery boulder will first drop towards its target, and explode once reached.