Script interface for the TriggerModule of a Particle System.
This module is useful for killing particles when they touch a set of collision shapes, or for calling a script command to let you apply custom particle behaviors when the trigger is activated.
The example code for MonoBehaviour.OnParticleTrigger shows how the callback type action works.
Particle System modules do not need to be reassigned back to the system; they are interfaces and not independent objects.